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Commit f66ffded authored by Linus Torvalds's avatar Linus Torvalds
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Merge branch 'sched-core-for-linus' of... 

Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (25 commits)
  sched: Fix SCHED_MC regression caused by change in sched cpu_power
  sched: Don't use possibly stale sched_class
  kthread, sched: Remove reference to kthread_create_on_cpu
  sched: cpuacct: Use bigger percpu counter batch values for stats counters
  percpu_counter: Make __percpu_counter_add an inline function on UP
  sched: Remove member rt_se from struct rt_rq
  sched: Change usage of rt_rq->rt_se to rt_rq->tg->rt_se[cpu]
  sched: Remove unused update_shares_locked()
  sched: Use for_each_bit
  sched: Queue a deboosted task to the head of the RT prio queue
  sched: Implement head queueing for sched_rt
  sched: Extend enqueue_task to allow head queueing
  sched: Remove USER_SCHED
  sched: Fix the place where group powers are updated
  sched: Assume *balance is valid
  sched: Remove load_balance_newidle()
  sched: Unify load_balance{,_newidle}()
  sched: Add a lock break for PREEMPT=y
  sched: Remove from fwd decls
  sched: Remove rq_iterator from move_one_task
  ...

Fix up trivial conflicts in kernel/sched.c
parents 2531216f dd5feea1
Hide whitespace changes
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Showing with 1976 additions and 2682 deletions
Documentation/feature-removal-schedule.txt
View file @ f66ffded
......@@ -6,21 +6,6 @@ be removed from this file.
---------------------------
What: USER_SCHED
When: 2.6.34
Why: USER_SCHED was implemented as a proof of concept for group scheduling.
The effect of USER_SCHED can already be achieved from userspace with
the help of libcgroup. The removal of USER_SCHED will also simplify
the scheduler code with the removal of one major ifdef. There are also
issues USER_SCHED has with USER_NS. A decision was taken not to fix
those and instead remove USER_SCHED. Also new group scheduling
features will not be implemented for USER_SCHED.
Who: Dhaval Giani <dhaval@linux.vnet.ibm.com>
---------------------------
What: PRISM54
When: 2.6.34
......
include/linux/kernel.h
View file @ f66ffded
......@@ -124,7 +124,7 @@ extern int _cond_resched(void);
#endif
#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
void __might_sleep(char *file, int line, int preempt_offset);
void __might_sleep(const char *file, int line, int preempt_offset);
/**
* might_sleep - annotation for functions that can sleep
*
......@@ -138,7 +138,8 @@ extern int _cond_resched(void);
# define might_sleep() \
do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
#else
static inline void __might_sleep(char *file, int line, int preempt_offset) { }
static inline void __might_sleep(const char *file, int line,
int preempt_offset) { }
# define might_sleep() do { might_resched(); } while (0)
#endif
......
include/linux/percpu_counter.h
View file @ f66ffded
......@@ -98,9 +98,6 @@ static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
fbc->count = amount;
}
#define __percpu_counter_add(fbc, amount, batch) \
percpu_counter_add(fbc, amount)
static inline void
percpu_counter_add(struct percpu_counter *fbc, s64 amount)
{
......@@ -109,6 +106,12 @@ percpu_counter_add(struct percpu_counter *fbc, s64 amount)
preempt_enable();
}
static inline void
__percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)
{
percpu_counter_add(fbc, amount);
}
static inline s64 percpu_counter_read(struct percpu_counter *fbc)
{
return fbc->count;
......
include/linux/sched.h
View file @ f66ffded
......@@ -740,14 +740,6 @@ struct user_struct {
uid_t uid;
struct user_namespace *user_ns;
#ifdef CONFIG_USER_SCHED
struct task_group *tg;
#ifdef CONFIG_SYSFS
struct kobject kobj;
struct delayed_work work;
#endif
#endif
#ifdef CONFIG_PERF_EVENTS
atomic_long_t locked_vm;
#endif
......@@ -1087,7 +1079,8 @@ struct sched_domain;
struct sched_class {
const struct sched_class *next;
void (*enqueue_task) (struct rq *rq, struct task_struct *p, int wakeup);
void (*enqueue_task) (struct rq *rq, struct task_struct *p, int wakeup,
bool head);
void (*dequeue_task) (struct rq *rq, struct task_struct *p, int sleep);
void (*yield_task) (struct rq *rq);
......@@ -1099,14 +1092,6 @@ struct sched_class {
#ifdef CONFIG_SMP
int (*select_task_rq)(struct task_struct *p, int sd_flag, int flags);
unsigned long (*load_balance) (struct rq *this_rq, int this_cpu,
struct rq *busiest, unsigned long max_load_move,
struct sched_domain *sd, enum cpu_idle_type idle,
int *all_pinned, int *this_best_prio);
int (*move_one_task) (struct rq *this_rq, int this_cpu,
struct rq *busiest, struct sched_domain *sd,
enum cpu_idle_type idle);
void (*pre_schedule) (struct rq *this_rq, struct task_struct *task);
void (*post_schedule) (struct rq *this_rq);
void (*task_waking) (struct rq *this_rq, struct task_struct *task);
......@@ -2520,13 +2505,9 @@ extern long sched_getaffinity(pid_t pid, struct cpumask *mask);
extern void normalize_rt_tasks(void);
#ifdef CONFIG_GROUP_SCHED
#ifdef CONFIG_CGROUP_SCHED
extern struct task_group init_task_group;
#ifdef CONFIG_USER_SCHED
extern struct task_group root_task_group;
extern void set_tg_uid(struct user_struct *user);
#endif
extern struct task_group *sched_create_group(struct task_group *parent);
extern void sched_destroy_group(struct task_group *tg);
......
init/Kconfig
View file @ f66ffded
......@@ -461,57 +461,6 @@ config LOG_BUF_SHIFT
config HAVE_UNSTABLE_SCHED_CLOCK
bool
config GROUP_SCHED
bool "Group CPU scheduler"
depends on EXPERIMENTAL
default n
help
This feature lets CPU scheduler recognize task groups and control CPU
bandwidth allocation to such task groups.
In order to create a group from arbitrary set of processes, use
CONFIG_CGROUPS. (See Control Group support.)
config FAIR_GROUP_SCHED
bool "Group scheduling for SCHED_OTHER"
depends on GROUP_SCHED
default GROUP_SCHED
config RT_GROUP_SCHED
bool "Group scheduling for SCHED_RR/FIFO"
depends on EXPERIMENTAL
depends on GROUP_SCHED
default n
help
This feature lets you explicitly allocate real CPU bandwidth
to users or control groups (depending on the "Basis for grouping tasks"
setting below. If enabled, it will also make it impossible to
schedule realtime tasks for non-root users until you allocate
realtime bandwidth for them.
See Documentation/scheduler/sched-rt-group.txt for more information.
choice
depends on GROUP_SCHED
prompt "Basis for grouping tasks"
default USER_SCHED
config USER_SCHED
bool "user id"
help
This option will choose userid as the basis for grouping
tasks, thus providing equal CPU bandwidth to each user.
config CGROUP_SCHED
bool "Control groups"
depends on CGROUPS
help
This option allows you to create arbitrary task groups
using the "cgroup" pseudo filesystem and control
the cpu bandwidth allocated to each such task group.
Refer to Documentation/cgroups/cgroups.txt for more
information on "cgroup" pseudo filesystem.
endchoice
menuconfig CGROUPS
boolean "Control Group support"
help
......@@ -632,6 +581,36 @@ config CGROUP_MEM_RES_CTLR_SWAP
Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
size is 4096bytes, 512k per 1Gbytes of swap.
menuconfig CGROUP_SCHED
bool "Group CPU scheduler"
depends on EXPERIMENTAL && CGROUPS
default n
help
This feature lets CPU scheduler recognize task groups and control CPU
bandwidth allocation to such task groups. It uses cgroups to group
tasks.
if CGROUP_SCHED
config FAIR_GROUP_SCHED
bool "Group scheduling for SCHED_OTHER"
depends on CGROUP_SCHED
default CGROUP_SCHED
config RT_GROUP_SCHED
bool "Group scheduling for SCHED_RR/FIFO"
depends on EXPERIMENTAL
depends on CGROUP_SCHED
default n
help
This feature lets you explicitly allocate real CPU bandwidth
to users or control groups (depending on the "Basis for grouping tasks"
setting below. If enabled, it will also make it impossible to
schedule realtime tasks for non-root users until you allocate
realtime bandwidth for them.
See Documentation/scheduler/sched-rt-group.txt for more information.
endif #CGROUP_SCHED
endif # CGROUPS
config MM_OWNER
......
kernel/ksysfs.c
View file @ f66ffded
......@@ -197,16 +197,8 @@ static int __init ksysfs_init(void)
goto group_exit;
}
/* create the /sys/kernel/uids/ directory */
error = uids_sysfs_init();
if (error)
goto notes_exit;
return 0;
notes_exit:
if (notes_size > 0)
sysfs_remove_bin_file(kernel_kobj, &notes_attr);
group_exit:
sysfs_remove_group(kernel_kobj, &kernel_attr_group);
kset_exit:
......
kernel/kthread.c
View file @ f66ffded
......@@ -101,7 +101,7 @@ static void create_kthread(struct kthread_create_info *create)
*
* Description: This helper function creates and names a kernel
* thread. The thread will be stopped: use wake_up_process() to start
* it. See also kthread_run(), kthread_create_on_cpu().
* it. See also kthread_run().
*
* When woken, the thread will run @threadfn() with @data as its
* argument. @threadfn() can either call do_exit() directly if it is a
......
kernel/sched.c
View file @ f66ffded
......@@ -233,7 +233,7 @@ static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
*/
static DEFINE_MUTEX(sched_domains_mutex);
#ifdef CONFIG_GROUP_SCHED
#ifdef CONFIG_CGROUP_SCHED
#include <linux/cgroup.h>
......@@ -243,13 +243,7 @@ static LIST_HEAD(task_groups);
/* task group related information */
struct task_group {
#ifdef CONFIG_CGROUP_SCHED
struct cgroup_subsys_state css;
#endif
#ifdef CONFIG_USER_SCHED
uid_t uid;
#endif
#ifdef CONFIG_FAIR_GROUP_SCHED
/* schedulable entities of this group on each cpu */
......@@ -274,35 +268,7 @@ struct task_group {
struct list_head children;
};
#ifdef CONFIG_USER_SCHED
/* Helper function to pass uid information to create_sched_user() */
void set_tg_uid(struct user_struct *user)
{
user->tg->uid = user->uid;
}
/*
* Root task group.
* Every UID task group (including init_task_group aka UID-0) will
* be a child to this group.
*/
struct task_group root_task_group;
#ifdef CONFIG_FAIR_GROUP_SCHED
/* Default task group's sched entity on each cpu */
static DEFINE_PER_CPU(struct sched_entity, init_sched_entity);
/* Default task group's cfs_rq on each cpu */
static DEFINE_PER_CPU_SHARED_ALIGNED(struct cfs_rq, init_tg_cfs_rq);
#endif /* CONFIG_FAIR_GROUP_SCHED */
#ifdef CONFIG_RT_GROUP_SCHED
static DEFINE_PER_CPU(struct sched_rt_entity, init_sched_rt_entity);
static DEFINE_PER_CPU_SHARED_ALIGNED(struct rt_rq, init_rt_rq_var);
#endif /* CONFIG_RT_GROUP_SCHED */
#else /* !CONFIG_USER_SCHED */
#define root_task_group init_task_group
#endif /* CONFIG_USER_SCHED */
/* task_group_lock serializes add/remove of task groups and also changes to
* a task group's cpu shares.
......@@ -318,11 +284,7 @@ static int root_task_group_empty(void)
}
#endif
#ifdef CONFIG_USER_SCHED
# define INIT_TASK_GROUP_LOAD (2*NICE_0_LOAD)
#else /* !CONFIG_USER_SCHED */
# define INIT_TASK_GROUP_LOAD NICE_0_LOAD
#endif /* CONFIG_USER_SCHED */
/*
* A weight of 0 or 1 can cause arithmetics problems.
......@@ -348,11 +310,7 @@ static inline struct task_group *task_group(struct task_struct *p)
{
struct task_group *tg;
#ifdef CONFIG_USER_SCHED
rcu_read_lock();
tg = __task_cred(p)->user->tg;
rcu_read_unlock();
#elif defined(CONFIG_CGROUP_SCHED)
#ifdef CONFIG_CGROUP_SCHED
tg = container_of(task_subsys_state(p, cpu_cgroup_subsys_id),
struct task_group, css);
#else
......@@ -383,7 +341,7 @@ static inline struct task_group *task_group(struct task_struct *p)
return NULL;
}
#endif /* CONFIG_GROUP_SCHED */
#endif /* CONFIG_CGROUP_SCHED */
/* CFS-related fields in a runqueue */
struct cfs_rq {
......@@ -478,7 +436,6 @@ struct rt_rq {
struct rq *rq;
struct list_head leaf_rt_rq_list;
struct task_group *tg;
struct sched_rt_entity *rt_se;
#endif
};
......@@ -1414,32 +1371,6 @@ static const u32 prio_to_wmult[40] = {
/* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153,
};
static void activate_task(struct rq *rq, struct task_struct *p, int wakeup);
/*
* runqueue iterator, to support SMP load-balancing between different
* scheduling classes, without having to expose their internal data
* structures to the load-balancing proper:
*/
struct rq_iterator {
void *arg;
struct task_struct *(*start)(void *);
struct task_struct *(*next)(void *);
};
#ifdef CONFIG_SMP
static unsigned long
balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
unsigned long max_load_move, struct sched_domain *sd,
enum cpu_idle_type idle, int *all_pinned,
int *this_best_prio, struct rq_iterator *iterator);
static int
iter_move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
struct sched_domain *sd, enum cpu_idle_type idle,
struct rq_iterator *iterator);
#endif
/* Time spent by the tasks of the cpu accounting group executing in ... */
enum cpuacct_stat_index {
CPUACCT_STAT_USER, /* ... user mode */
......@@ -1725,16 +1656,6 @@ static void update_shares(struct sched_domain *sd)
}
}
static void update_shares_locked(struct rq *rq, struct sched_domain *sd)
{
if (root_task_group_empty())
return;
raw_spin_unlock(&rq->lock);
update_shares(sd);
raw_spin_lock(&rq->lock);
}
static void update_h_load(long cpu)
{
if (root_task_group_empty())
......@@ -1749,10 +1670,6 @@ static inline void update_shares(struct sched_domain *sd)
{
}
static inline void update_shares_locked(struct rq *rq, struct sched_domain *sd)
{
}
#endif
#ifdef CONFIG_PREEMPT
......@@ -1829,6 +1746,51 @@ static inline void double_unlock_balance(struct rq *this_rq, struct rq *busiest)
raw_spin_unlock(&busiest->lock);
lock_set_subclass(&this_rq->lock.dep_map, 0, _RET_IP_);
}
/*
* double_rq_lock - safely lock two runqueues
*
* Note this does not disable interrupts like task_rq_lock,
* you need to do so manually before calling.
*/
static void double_rq_lock(struct rq *rq1, struct rq *rq2)
__acquires(rq1->lock)
__acquires(rq2->lock)
{
BUG_ON(!irqs_disabled());
if (rq1 == rq2) {
raw_spin_lock(&rq1->lock);
__acquire(rq2->lock); /* Fake it out ;) */
} else {
if (rq1 < rq2) {
raw_spin_lock(&rq1->lock);
raw_spin_lock_nested(&rq2->lock, SINGLE_DEPTH_NESTING);
} else {
raw_spin_lock(&rq2->lock);
raw_spin_lock_nested(&rq1->lock, SINGLE_DEPTH_NESTING);
}
}
update_rq_clock(rq1);
update_rq_clock(rq2);
}
/*
* double_rq_unlock - safely unlock two runqueues
*
* Note this does not restore interrupts like task_rq_unlock,
* you need to do so manually after calling.
*/
static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
__releases(rq1->lock)
__releases(rq2->lock)
{
raw_spin_unlock(&rq1->lock);
if (rq1 != rq2)
raw_spin_unlock(&rq2->lock);
else
__release(rq2->lock);
}
#endif
#ifdef CONFIG_FAIR_GROUP_SCHED
......@@ -1858,18 +1820,14 @@ static inline void __set_task_cpu(struct task_struct *p, unsigned int cpu)
#endif
}
#include "sched_stats.h"
#include "sched_idletask.c"
#include "sched_fair.c"
#include "sched_rt.c"
#ifdef CONFIG_SCHED_DEBUG
# include "sched_debug.c"
#endif
static const struct sched_class rt_sched_class;
#define sched_class_highest (&rt_sched_class)
#define for_each_class(class) \
for (class = sched_class_highest; class; class = class->next)
#include "sched_stats.h"
static void inc_nr_running(struct rq *rq)
{
rq->nr_running++;
......@@ -1907,13 +1865,14 @@ static void update_avg(u64 *avg, u64 sample)
*avg += diff >> 3;
}
static void enqueue_task(struct rq *rq, struct task_struct *p, int wakeup)
static void
enqueue_task(struct rq *rq, struct task_struct *p, int wakeup, bool head)
{
if (wakeup)
p->se.start_runtime = p->se.sum_exec_runtime;
sched_info_queued(p);
p->sched_class->enqueue_task(rq, p, wakeup);
p->sched_class->enqueue_task(rq, p, wakeup, head);
p->se.on_rq = 1;
}
......@@ -1935,6 +1894,37 @@ static void dequeue_task(struct rq *rq, struct task_struct *p, int sleep)
p->se.on_rq = 0;
}
/*
* activate_task - move a task to the runqueue.
*/
static void activate_task(struct rq *rq, struct task_struct *p, int wakeup)
{
if (task_contributes_to_load(p))
rq->nr_uninterruptible--;
enqueue_task(rq, p, wakeup, false);
inc_nr_running(rq);
}
/*
* deactivate_task - remove a task from the runqueue.
*/
static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep)
{
if (task_contributes_to_load(p))
rq->nr_uninterruptible++;
dequeue_task(rq, p, sleep);
dec_nr_running(rq);
}
#include "sched_idletask.c"
#include "sched_fair.c"
#include "sched_rt.c"
#ifdef CONFIG_SCHED_DEBUG
# include "sched_debug.c"
#endif
/*
* __normal_prio - return the priority that is based on the static prio
*/
......@@ -1981,30 +1971,6 @@ static int effective_prio(struct task_struct *p)
return p->prio;
}
/*
* activate_task - move a task to the runqueue.
*/
static void activate_task(struct rq *rq, struct task_struct *p, int wakeup)
{
if (task_contributes_to_load(p))
rq->nr_uninterruptible--;
enqueue_task(rq, p, wakeup);
inc_nr_running(rq);
}
/*
* deactivate_task - remove a task from the runqueue.
*/
static void deactivate_task(struct rq *rq, struct task_struct *p, int sleep)
{
if (task_contributes_to_load(p))
rq->nr_uninterruptible++;
dequeue_task(rq, p, sleep);
dec_nr_running(rq);
}
/**
* task_curr - is this task currently executing on a CPU?
* @p: the task in question.
......@@ -2988,2031 +2954,211 @@ unsigned long nr_running(void)
for_each_online_cpu(i)
sum += cpu_rq(i)->nr_running;
return sum;
}
unsigned long nr_uninterruptible(void)
{
unsigned long i, sum = 0;
for_each_possible_cpu(i)
sum += cpu_rq(i)->nr_uninterruptible;
/*
* Since we read the counters lockless, it might be slightly
* inaccurate. Do not allow it to go below zero though:
*/
if (unlikely((long)sum < 0))
sum = 0;
return sum;
}
unsigned long long nr_context_switches(void)
{
int i;
unsigned long long sum = 0;
for_each_possible_cpu(i)
sum += cpu_rq(i)->nr_switches;
return sum;
}
unsigned long nr_iowait(void)
{
unsigned long i, sum = 0;
for_each_possible_cpu(i)
sum += atomic_read(&cpu_rq(i)->nr_iowait);
return sum;
}
unsigned long nr_iowait_cpu(void)
{
struct rq *this = this_rq();
return atomic_read(&this->nr_iowait);
}
unsigned long this_cpu_load(void)
{
struct rq *this = this_rq();
return this->cpu_load[0];
}
/* Variables and functions for calc_load */
static atomic_long_t calc_load_tasks;
static unsigned long calc_load_update;
unsigned long avenrun[3];
EXPORT_SYMBOL(avenrun);
/**
* get_avenrun - get the load average array
* @loads: pointer to dest load array
* @offset: offset to add
* @shift: shift count to shift the result left
*
* These values are estimates at best, so no need for locking.
*/
void get_avenrun(unsigned long *loads, unsigned long offset, int shift)
{
loads[0] = (avenrun[0] + offset) << shift;
loads[1] = (avenrun[1] + offset) << shift;
loads[2] = (avenrun[2] + offset) << shift;
}
static unsigned long
calc_load(unsigned long load, unsigned long exp, unsigned long active)
{
load *= exp;
load += active * (FIXED_1 - exp);
return load >> FSHIFT;
}
/*
* calc_load - update the avenrun load estimates 10 ticks after the
* CPUs have updated calc_load_tasks.
*/
void calc_global_load(void)
{
unsigned long upd = calc_load_update + 10;
long active;
if (time_before(jiffies, upd))
return;
active = atomic_long_read(&calc_load_tasks);
active = active > 0 ? active * FIXED_1 : 0;
avenrun[0] = calc_load(avenrun[0], EXP_1, active);
avenrun[1] = calc_load(avenrun[1], EXP_5, active);
avenrun[2] = calc_load(avenrun[2], EXP_15, active);
calc_load_update += LOAD_FREQ;
}
/*
* Either called from update_cpu_load() or from a cpu going idle
*/
static void calc_load_account_active(struct rq *this_rq)
{
long nr_active, delta;
nr_active = this_rq->nr_running;
nr_active += (long) this_rq->nr_uninterruptible;
if (nr_active != this_rq->calc_load_active) {
delta = nr_active - this_rq->calc_load_active;
this_rq->calc_load_active = nr_active;
atomic_long_add(delta, &calc_load_tasks);
}
}
/*
* Update rq->cpu_load[] statistics. This function is usually called every
* scheduler tick (TICK_NSEC).
*/
static void update_cpu_load(struct rq *this_rq)
{
unsigned long this_load = this_rq->load.weight;
int i, scale;
this_rq->nr_load_updates++;
/* Update our load: */
for (i = 0, scale = 1; i < CPU_LOAD_IDX_MAX; i++, scale += scale) {
unsigned long old_load, new_load;
/* scale is effectively 1 << i now, and >> i divides by scale */
old_load = this_rq->cpu_load[i];
new_load = this_load;
/*
* Round up the averaging division if load is increasing. This
* prevents us from getting stuck on 9 if the load is 10, for
* example.
*/
if (new_load > old_load)
new_load += scale-1;
this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) >> i;
}
if (time_after_eq(jiffies, this_rq->calc_load_update)) {
this_rq->calc_load_update += LOAD_FREQ;
calc_load_account_active(this_rq);
}
}
#ifdef CONFIG_SMP
/*
* double_rq_lock - safely lock two runqueues
*
* Note this does not disable interrupts like task_rq_lock,
* you need to do so manually before calling.
*/
static void double_rq_lock(struct rq *rq1, struct rq *rq2)
__acquires(rq1->lock)
__acquires(rq2->lock)
{
BUG_ON(!irqs_disabled());
if (rq1 == rq2) {
raw_spin_lock(&rq1->lock);
__acquire(rq2->lock); /* Fake it out ;) */
} else {
if (rq1 < rq2) {
raw_spin_lock(&rq1->lock);
raw_spin_lock_nested(&rq2->lock, SINGLE_DEPTH_NESTING);
} else {
raw_spin_lock(&rq2->lock);
raw_spin_lock_nested(&rq1->lock, SINGLE_DEPTH_NESTING);
}
}
update_rq_clock(rq1);
update_rq_clock(rq2);
}
/*
* double_rq_unlock - safely unlock two runqueues
*
* Note this does not restore interrupts like task_rq_unlock,
* you need to do so manually after calling.
*/
static void double_rq_unlock(struct rq *rq1, struct rq *rq2)
__releases(rq1->lock)
__releases(rq2->lock)
{
raw_spin_unlock(&rq1->lock);
if (rq1 != rq2)
raw_spin_unlock(&rq2->lock);
else
__release(rq2->lock);
}
/*
* sched_exec - execve() is a valuable balancing opportunity, because at
* this point the task has the smallest effective memory and cache footprint.
*/
void sched_exec(void)
{
struct task_struct *p = current;
struct migration_req req;
int dest_cpu, this_cpu;
unsigned long flags;
struct rq *rq;
again:
this_cpu = get_cpu();
dest_cpu = select_task_rq(p, SD_BALANCE_EXEC, 0);
if (dest_cpu == this_cpu) {
put_cpu();
return;
}
rq = task_rq_lock(p, &flags);
put_cpu();
/*
* select_task_rq() can race against ->cpus_allowed
*/
if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed)
|| unlikely(!cpu_active(dest_cpu))) {
task_rq_unlock(rq, &flags);
goto again;
}
/* force the process onto the specified CPU */
if (migrate_task(p, dest_cpu, &req)) {
/* Need to wait for migration thread (might exit: take ref). */
struct task_struct *mt = rq->migration_thread;
get_task_struct(mt);
task_rq_unlock(rq, &flags);
wake_up_process(mt);
put_task_struct(mt);
wait_for_completion(&req.done);
return;
}
task_rq_unlock(rq, &flags);
}
/*
* pull_task - move a task from a remote runqueue to the local runqueue.
* Both runqueues must be locked.
*/
static void pull_task(struct rq *src_rq, struct task_struct *p,
struct rq *this_rq, int this_cpu)
{
deactivate_task(src_rq, p, 0);
set_task_cpu(p, this_cpu);
activate_task(this_rq, p, 0);
check_preempt_curr(this_rq, p, 0);
}
/*
* can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
*/
static
int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
struct sched_domain *sd, enum cpu_idle_type idle,
int *all_pinned)
{
int tsk_cache_hot = 0;
/*
* We do not migrate tasks that are:
* 1) running (obviously), or
* 2) cannot be migrated to this CPU due to cpus_allowed, or
* 3) are cache-hot on their current CPU.
*/
if (!cpumask_test_cpu(this_cpu, &p->cpus_allowed)) {
schedstat_inc(p, se.nr_failed_migrations_affine);
return 0;
}
*all_pinned = 0;
if (task_running(rq, p)) {
schedstat_inc(p, se.nr_failed_migrations_running);
return 0;
}
/*
* Aggressive migration if:
* 1) task is cache cold, or
* 2) too many balance attempts have failed.
*/
tsk_cache_hot = task_hot(p, rq->clock, sd);
if (!tsk_cache_hot ||
sd->nr_balance_failed > sd->cache_nice_tries) {
#ifdef CONFIG_SCHEDSTATS
if (tsk_cache_hot) {
schedstat_inc(sd, lb_hot_gained[idle]);
schedstat_inc(p, se.nr_forced_migrations);
}
#endif
return 1;
}
if (tsk_cache_hot) {
schedstat_inc(p, se.nr_failed_migrations_hot);
return 0;
}
return 1;
}
static unsigned long
balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
unsigned long max_load_move, struct sched_domain *sd,
enum cpu_idle_type idle, int *all_pinned,
int *this_best_prio, struct rq_iterator *iterator)
{
int loops = 0, pulled = 0, pinned = 0;
struct task_struct *p;
long rem_load_move = max_load_move;
if (max_load_move == 0)
goto out;
pinned = 1;
/*
* Start the load-balancing iterator:
*/
p = iterator->start(iterator->arg);
next:
if (!p || loops++ > sysctl_sched_nr_migrate)
goto out;
if ((p->se.load.weight >> 1) > rem_load_move ||
!can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) {
p = iterator->next(iterator->arg);
goto next;
}
pull_task(busiest, p, this_rq, this_cpu);
pulled++;
rem_load_move -= p->se.load.weight;
#ifdef CONFIG_PREEMPT
/*
* NEWIDLE balancing is a source of latency, so preemptible kernels
* will stop after the first task is pulled to minimize the critical
* section.
*/
if (idle == CPU_NEWLY_IDLE)
goto out;
#endif
/*
* We only want to steal up to the prescribed amount of weighted load.
*/
if (rem_load_move > 0) {
if (p->prio < *this_best_prio)
*this_best_prio = p->prio;
p = iterator->next(iterator->arg);
goto next;
}
out:
/*
* Right now, this is one of only two places pull_task() is called,
* so we can safely collect pull_task() stats here rather than
* inside pull_task().
*/
schedstat_add(sd, lb_gained[idle], pulled);
if (all_pinned)
*all_pinned = pinned;
return max_load_move - rem_load_move;
}
/*
* move_tasks tries to move up to max_load_move weighted load from busiest to
* this_rq, as part of a balancing operation within domain "sd".
* Returns 1 if successful and 0 otherwise.
*
* Called with both runqueues locked.
*/
static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
unsigned long max_load_move,
struct sched_domain *sd, enum cpu_idle_type idle,
int *all_pinned)
{
const struct sched_class *class = sched_class_highest;
unsigned long total_load_moved = 0;
int this_best_prio = this_rq->curr->prio;
do {
total_load_moved +=
class->load_balance(this_rq, this_cpu, busiest,
max_load_move - total_load_moved,
sd, idle, all_pinned, &this_best_prio);
class = class->next;
#ifdef CONFIG_PREEMPT
/*
* NEWIDLE balancing is a source of latency, so preemptible
* kernels will stop after the first task is pulled to minimize
* the critical section.
*/
if (idle == CPU_NEWLY_IDLE && this_rq->nr_running)
break;
#endif
} while (class && max_load_move > total_load_moved);
return total_load_moved > 0;
}
static int
iter_move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
struct sched_domain *sd, enum cpu_idle_type idle,
struct rq_iterator *iterator)
{
struct task_struct *p = iterator->start(iterator->arg);
int pinned = 0;
while (p) {
if (can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned)) {
pull_task(busiest, p, this_rq, this_cpu);
/*
* Right now, this is only the second place pull_task()
* is called, so we can safely collect pull_task()
* stats here rather than inside pull_task().
*/
schedstat_inc(sd, lb_gained[idle]);
return 1;
}
p = iterator->next(iterator->arg);
}
return 0;
}
/*
* move_one_task tries to move exactly one task from busiest to this_rq, as
* part of active balancing operations within "domain".
* Returns 1 if successful and 0 otherwise.
*
* Called with both runqueues locked.
*/
static int move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
struct sched_domain *sd, enum cpu_idle_type idle)
{
const struct sched_class *class;
for_each_class(class) {
if (class->move_one_task(this_rq, this_cpu, busiest, sd, idle))
return 1;
}
return 0;
}
/********** Helpers for find_busiest_group ************************/
/*
* sd_lb_stats - Structure to store the statistics of a sched_domain
* during load balancing.
*/
struct sd_lb_stats {
struct sched_group *busiest; /* Busiest group in this sd */
struct sched_group *this; /* Local group in this sd */
unsigned long total_load; /* Total load of all groups in sd */
unsigned long total_pwr; /* Total power of all groups in sd */
unsigned long avg_load; /* Average load across all groups in sd */
/** Statistics of this group */
unsigned long this_load;
unsigned long this_load_per_task;
unsigned long this_nr_running;
/* Statistics of the busiest group */
unsigned long max_load;
unsigned long busiest_load_per_task;
unsigned long busiest_nr_running;
int group_imb; /* Is there imbalance in this sd */
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
int power_savings_balance; /* Is powersave balance needed for this sd */
struct sched_group *group_min; /* Least loaded group in sd */
struct sched_group *group_leader; /* Group which relieves group_min */
unsigned long min_load_per_task; /* load_per_task in group_min */
unsigned long leader_nr_running; /* Nr running of group_leader */
unsigned long min_nr_running; /* Nr running of group_min */
#endif
};
/*
* sg_lb_stats - stats of a sched_group required for load_balancing
*/
struct sg_lb_stats {
unsigned long avg_load; /*Avg load across the CPUs of the group */
unsigned long group_load; /* Total load over the CPUs of the group */
unsigned long sum_nr_running; /* Nr tasks running in the group */
unsigned long sum_weighted_load; /* Weighted load of group's tasks */
unsigned long group_capacity;
int group_imb; /* Is there an imbalance in the group ? */
};
/**
* group_first_cpu - Returns the first cpu in the cpumask of a sched_group.
* @group: The group whose first cpu is to be returned.
*/
static inline unsigned int group_first_cpu(struct sched_group *group)
{
return cpumask_first(sched_group_cpus(group));
}
/**
* get_sd_load_idx - Obtain the load index for a given sched domain.
* @sd: The sched_domain whose load_idx is to be obtained.
* @idle: The Idle status of the CPU for whose sd load_icx is obtained.
*/
static inline int get_sd_load_idx(struct sched_domain *sd,
enum cpu_idle_type idle)
{
int load_idx;
switch (idle) {
case CPU_NOT_IDLE:
load_idx = sd->busy_idx;
break;
case CPU_NEWLY_IDLE:
load_idx = sd->newidle_idx;
break;
default:
load_idx = sd->idle_idx;
break;
}
return load_idx;
}
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
/**
* init_sd_power_savings_stats - Initialize power savings statistics for
* the given sched_domain, during load balancing.
*
* @sd: Sched domain whose power-savings statistics are to be initialized.
* @sds: Variable containing the statistics for sd.
* @idle: Idle status of the CPU at which we're performing load-balancing.
*/
static inline void init_sd_power_savings_stats(struct sched_domain *sd,
struct sd_lb_stats *sds, enum cpu_idle_type idle)
{
/*
* Busy processors will not participate in power savings
* balance.
*/
if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
sds->power_savings_balance = 0;
else {
sds->power_savings_balance = 1;
sds->min_nr_running = ULONG_MAX;
sds->leader_nr_running = 0;
}
}
/**
* update_sd_power_savings_stats - Update the power saving stats for a
* sched_domain while performing load balancing.
*
* @group: sched_group belonging to the sched_domain under consideration.
* @sds: Variable containing the statistics of the sched_domain
* @local_group: Does group contain the CPU for which we're performing
* load balancing ?
* @sgs: Variable containing the statistics of the group.
*/
static inline void update_sd_power_savings_stats(struct sched_group *group,
struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
{
if (!sds->power_savings_balance)
return;
/*
* If the local group is idle or completely loaded
* no need to do power savings balance at this domain
*/
if (local_group && (sds->this_nr_running >= sgs->group_capacity ||
!sds->this_nr_running))
sds->power_savings_balance = 0;
/*
* If a group is already running at full capacity or idle,
* don't include that group in power savings calculations
*/
if (!sds->power_savings_balance ||
sgs->sum_nr_running >= sgs->group_capacity ||
!sgs->sum_nr_running)
return;
/*
* Calculate the group which has the least non-idle load.
* This is the group from where we need to pick up the load
* for saving power
*/
if ((sgs->sum_nr_running < sds->min_nr_running) ||
(sgs->sum_nr_running == sds->min_nr_running &&
group_first_cpu(group) > group_first_cpu(sds->group_min))) {
sds->group_min = group;
sds->min_nr_running = sgs->sum_nr_running;
sds->min_load_per_task = sgs->sum_weighted_load /
sgs->sum_nr_running;
}
/*
* Calculate the group which is almost near its
* capacity but still has some space to pick up some load
* from other group and save more power
*/
if (sgs->sum_nr_running + 1 > sgs->group_capacity)
return;
if (sgs->sum_nr_running > sds->leader_nr_running ||
(sgs->sum_nr_running == sds->leader_nr_running &&
group_first_cpu(group) < group_first_cpu(sds->group_leader))) {
sds->group_leader = group;
sds->leader_nr_running = sgs->sum_nr_running;
}
}
/**
* check_power_save_busiest_group - see if there is potential for some power-savings balance
* @sds: Variable containing the statistics of the sched_domain
* under consideration.
* @this_cpu: Cpu at which we're currently performing load-balancing.
* @imbalance: Variable to store the imbalance.
*
* Description:
* Check if we have potential to perform some power-savings balance.
* If yes, set the busiest group to be the least loaded group in the
* sched_domain, so that it's CPUs can be put to idle.
*
* Returns 1 if there is potential to perform power-savings balance.
* Else returns 0.
*/
static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
int this_cpu, unsigned long *imbalance)
{
if (!sds->power_savings_balance)
return 0;
if (sds->this != sds->group_leader ||
sds->group_leader == sds->group_min)
return 0;
*imbalance = sds->min_load_per_task;
sds->busiest = sds->group_min;
return 1;
}
#else /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
static inline void init_sd_power_savings_stats(struct sched_domain *sd,
struct sd_lb_stats *sds, enum cpu_idle_type idle)
{
return;
}
static inline void update_sd_power_savings_stats(struct sched_group *group,
struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
{
return;
}
static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
int this_cpu, unsigned long *imbalance)
{
return 0;
}
#endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
{
return SCHED_LOAD_SCALE;
}
unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu)
{
return default_scale_freq_power(sd, cpu);
}
unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu)
{
unsigned long weight = cpumask_weight(sched_domain_span(sd));
unsigned long smt_gain = sd->smt_gain;
smt_gain /= weight;
return smt_gain;
}
unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
{
return default_scale_smt_power(sd, cpu);
}
unsigned long scale_rt_power(int cpu)
{
struct rq *rq = cpu_rq(cpu);
u64 total, available;
sched_avg_update(rq);
total = sched_avg_period() + (rq->clock - rq->age_stamp);
available = total - rq->rt_avg;
if (unlikely((s64)total < SCHED_LOAD_SCALE))
total = SCHED_LOAD_SCALE;
total >>= SCHED_LOAD_SHIFT;
return div_u64(available, total);
}
static void update_cpu_power(struct sched_domain *sd, int cpu)
{
unsigned long weight = cpumask_weight(sched_domain_span(sd));
unsigned long power = SCHED_LOAD_SCALE;
struct sched_group *sdg = sd->groups;
if (sched_feat(ARCH_POWER))
power *= arch_scale_freq_power(sd, cpu);
else
power *= default_scale_freq_power(sd, cpu);
power >>= SCHED_LOAD_SHIFT;
if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
if (sched_feat(ARCH_POWER))
power *= arch_scale_smt_power(sd, cpu);
else
power *= default_scale_smt_power(sd, cpu);
power >>= SCHED_LOAD_SHIFT;
}
power *= scale_rt_power(cpu);
power >>= SCHED_LOAD_SHIFT;
if (!power)
power = 1;
sdg->cpu_power = power;
}
static void update_group_power(struct sched_domain *sd, int cpu)
{
struct sched_domain *child = sd->child;
struct sched_group *group, *sdg = sd->groups;
unsigned long power;
if (!child) {
update_cpu_power(sd, cpu);
return;
}
power = 0;
group = child->groups;
do {
power += group->cpu_power;
group = group->next;
} while (group != child->groups);
sdg->cpu_power = power;
}
/**
* update_sg_lb_stats - Update sched_group's statistics for load balancing.
* @sd: The sched_domain whose statistics are to be updated.
* @group: sched_group whose statistics are to be updated.
* @this_cpu: Cpu for which load balance is currently performed.
* @idle: Idle status of this_cpu
* @load_idx: Load index of sched_domain of this_cpu for load calc.
* @sd_idle: Idle status of the sched_domain containing group.
* @local_group: Does group contain this_cpu.
* @cpus: Set of cpus considered for load balancing.
* @balance: Should we balance.
* @sgs: variable to hold the statistics for this group.
*/
static inline void update_sg_lb_stats(struct sched_domain *sd,
struct sched_group *group, int this_cpu,
enum cpu_idle_type idle, int load_idx, int *sd_idle,
int local_group, const struct cpumask *cpus,
int *balance, struct sg_lb_stats *sgs)
{
unsigned long load, max_cpu_load, min_cpu_load;
int i;
unsigned int balance_cpu = -1, first_idle_cpu = 0;
unsigned long sum_avg_load_per_task;
unsigned long avg_load_per_task;
if (local_group) {
balance_cpu = group_first_cpu(group);
if (balance_cpu == this_cpu)
update_group_power(sd, this_cpu);
}
/* Tally up the load of all CPUs in the group */
sum_avg_load_per_task = avg_load_per_task = 0;
max_cpu_load = 0;
min_cpu_load = ~0UL;
for_each_cpu_and(i, sched_group_cpus(group), cpus) {
struct rq *rq = cpu_rq(i);
if (*sd_idle && rq->nr_running)
*sd_idle = 0;
/* Bias balancing toward cpus of our domain */
if (local_group) {
if (idle_cpu(i) && !first_idle_cpu) {
first_idle_cpu = 1;
balance_cpu = i;
}
load = target_load(i, load_idx);
} else {
load = source_load(i, load_idx);
if (load > max_cpu_load)
max_cpu_load = load;
if (min_cpu_load > load)
min_cpu_load = load;
}
sgs->group_load += load;
sgs->sum_nr_running += rq->nr_running;
sgs->sum_weighted_load += weighted_cpuload(i);
sum_avg_load_per_task += cpu_avg_load_per_task(i);
}
/*
* First idle cpu or the first cpu(busiest) in this sched group
* is eligible for doing load balancing at this and above
* domains. In the newly idle case, we will allow all the cpu's
* to do the newly idle load balance.
*/
if (idle != CPU_NEWLY_IDLE && local_group &&
balance_cpu != this_cpu && balance) {
*balance = 0;
return;
}
/* Adjust by relative CPU power of the group */
sgs->avg_load = (sgs->group_load * SCHED_LOAD_SCALE) / group->cpu_power;
/*
* Consider the group unbalanced when the imbalance is larger
* than the average weight of two tasks.
*
* APZ: with cgroup the avg task weight can vary wildly and
* might not be a suitable number - should we keep a
* normalized nr_running number somewhere that negates
* the hierarchy?
*/
avg_load_per_task = (sum_avg_load_per_task * SCHED_LOAD_SCALE) /
group->cpu_power;
if ((max_cpu_load - min_cpu_load) > 2*avg_load_per_task)
sgs->group_imb = 1;
sgs->group_capacity =
DIV_ROUND_CLOSEST(group->cpu_power, SCHED_LOAD_SCALE);
}
/**
* update_sd_lb_stats - Update sched_group's statistics for load balancing.
* @sd: sched_domain whose statistics are to be updated.
* @this_cpu: Cpu for which load balance is currently performed.
* @idle: Idle status of this_cpu
* @sd_idle: Idle status of the sched_domain containing group.
* @cpus: Set of cpus considered for load balancing.
* @balance: Should we balance.
* @sds: variable to hold the statistics for this sched_domain.
*/
static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu,
enum cpu_idle_type idle, int *sd_idle,
const struct cpumask *cpus, int *balance,
struct sd_lb_stats *sds)
{
struct sched_domain *child = sd->child;
struct sched_group *group = sd->groups;
struct sg_lb_stats sgs;
int load_idx, prefer_sibling = 0;
if (child && child->flags & SD_PREFER_SIBLING)
prefer_sibling = 1;
init_sd_power_savings_stats(sd, sds, idle);
load_idx = get_sd_load_idx(sd, idle);
do {
int local_group;
local_group = cpumask_test_cpu(this_cpu,
sched_group_cpus(group));
memset(&sgs, 0, sizeof(sgs));
update_sg_lb_stats(sd, group, this_cpu, idle, load_idx, sd_idle,
local_group, cpus, balance, &sgs);
if (local_group && balance && !(*balance))
return;
sds->total_load += sgs.group_load;
sds->total_pwr += group->cpu_power;
/*
* In case the child domain prefers tasks go to siblings
* first, lower the group capacity to one so that we'll try
* and move all the excess tasks away.
*/
if (prefer_sibling)
sgs.group_capacity = min(sgs.group_capacity, 1UL);
if (local_group) {
sds->this_load = sgs.avg_load;
sds->this = group;
sds->this_nr_running = sgs.sum_nr_running;
sds->this_load_per_task = sgs.sum_weighted_load;
} else if (sgs.avg_load > sds->max_load &&
(sgs.sum_nr_running > sgs.group_capacity ||
sgs.group_imb)) {
sds->max_load = sgs.avg_load;
sds->busiest = group;
sds->busiest_nr_running = sgs.sum_nr_running;
sds->busiest_load_per_task = sgs.sum_weighted_load;
sds->group_imb = sgs.group_imb;
}
update_sd_power_savings_stats(group, sds, local_group, &sgs);
group = group->next;
} while (group != sd->groups);
}
/**
* fix_small_imbalance - Calculate the minor imbalance that exists
* amongst the groups of a sched_domain, during
* load balancing.
* @sds: Statistics of the sched_domain whose imbalance is to be calculated.
* @this_cpu: The cpu at whose sched_domain we're performing load-balance.
* @imbalance: Variable to store the imbalance.
*/
static inline void fix_small_imbalance(struct sd_lb_stats *sds,
int this_cpu, unsigned long *imbalance)
{
unsigned long tmp, pwr_now = 0, pwr_move = 0;
unsigned int imbn = 2;
if (sds->this_nr_running) {
sds->this_load_per_task /= sds->this_nr_running;
if (sds->busiest_load_per_task >
sds->this_load_per_task)
imbn = 1;
} else
sds->this_load_per_task =
cpu_avg_load_per_task(this_cpu);
if (sds->max_load - sds->this_load + sds->busiest_load_per_task >=
sds->busiest_load_per_task * imbn) {
*imbalance = sds->busiest_load_per_task;
return;
}
/*
* OK, we don't have enough imbalance to justify moving tasks,
* however we may be able to increase total CPU power used by
* moving them.
*/
pwr_now += sds->busiest->cpu_power *
min(sds->busiest_load_per_task, sds->max_load);
pwr_now += sds->this->cpu_power *
min(sds->this_load_per_task, sds->this_load);
pwr_now /= SCHED_LOAD_SCALE;
/* Amount of load we'd subtract */
tmp = (sds->busiest_load_per_task * SCHED_LOAD_SCALE) /
sds->busiest->cpu_power;
if (sds->max_load > tmp)
pwr_move += sds->busiest->cpu_power *
min(sds->busiest_load_per_task, sds->max_load - tmp);
/* Amount of load we'd add */
if (sds->max_load * sds->busiest->cpu_power <
sds->busiest_load_per_task * SCHED_LOAD_SCALE)
tmp = (sds->max_load * sds->busiest->cpu_power) /
sds->this->cpu_power;
else
tmp = (sds->busiest_load_per_task * SCHED_LOAD_SCALE) /
sds->this->cpu_power;
pwr_move += sds->this->cpu_power *
min(sds->this_load_per_task, sds->this_load + tmp);
pwr_move /= SCHED_LOAD_SCALE;
/* Move if we gain throughput */
if (pwr_move > pwr_now)
*imbalance = sds->busiest_load_per_task;
}
/**
* calculate_imbalance - Calculate the amount of imbalance present within the
* groups of a given sched_domain during load balance.
* @sds: statistics of the sched_domain whose imbalance is to be calculated.
* @this_cpu: Cpu for which currently load balance is being performed.
* @imbalance: The variable to store the imbalance.
*/
static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu,
unsigned long *imbalance)
{
unsigned long max_pull;
/*
* In the presence of smp nice balancing, certain scenarios can have
* max load less than avg load(as we skip the groups at or below
* its cpu_power, while calculating max_load..)
*/
if (sds->max_load < sds->avg_load) {
*imbalance = 0;
return fix_small_imbalance(sds, this_cpu, imbalance);
}
/* Don't want to pull so many tasks that a group would go idle */
max_pull = min(sds->max_load - sds->avg_load,
sds->max_load - sds->busiest_load_per_task);
/* How much load to actually move to equalise the imbalance */
*imbalance = min(max_pull * sds->busiest->cpu_power,
(sds->avg_load - sds->this_load) * sds->this->cpu_power)
/ SCHED_LOAD_SCALE;
/*
* if *imbalance is less than the average load per runnable task
* there is no gaurantee that any tasks will be moved so we'll have
* a think about bumping its value to force at least one task to be
* moved
*/
if (*imbalance < sds->busiest_load_per_task)
return fix_small_imbalance(sds, this_cpu, imbalance);
}
/******* find_busiest_group() helpers end here *********************/
/**
* find_busiest_group - Returns the busiest group within the sched_domain
* if there is an imbalance. If there isn't an imbalance, and
* the user has opted for power-savings, it returns a group whose
* CPUs can be put to idle by rebalancing those tasks elsewhere, if
* such a group exists.
*
* Also calculates the amount of weighted load which should be moved
* to restore balance.
*
* @sd: The sched_domain whose busiest group is to be returned.
* @this_cpu: The cpu for which load balancing is currently being performed.
* @imbalance: Variable which stores amount of weighted load which should
* be moved to restore balance/put a group to idle.
* @idle: The idle status of this_cpu.
* @sd_idle: The idleness of sd
* @cpus: The set of CPUs under consideration for load-balancing.
* @balance: Pointer to a variable indicating if this_cpu
* is the appropriate cpu to perform load balancing at this_level.
*
* Returns: - the busiest group if imbalance exists.
* - If no imbalance and user has opted for power-savings balance,
* return the least loaded group whose CPUs can be
* put to idle by rebalancing its tasks onto our group.
*/
static struct sched_group *
find_busiest_group(struct sched_domain *sd, int this_cpu,
unsigned long *imbalance, enum cpu_idle_type idle,
int *sd_idle, const struct cpumask *cpus, int *balance)
{
struct sd_lb_stats sds;
memset(&sds, 0, sizeof(sds));
/*
* Compute the various statistics relavent for load balancing at
* this level.
*/
update_sd_lb_stats(sd, this_cpu, idle, sd_idle, cpus,
balance, &sds);
/* Cases where imbalance does not exist from POV of this_cpu */
/* 1) this_cpu is not the appropriate cpu to perform load balancing
* at this level.
* 2) There is no busy sibling group to pull from.
* 3) This group is the busiest group.
* 4) This group is more busy than the avg busieness at this
* sched_domain.
* 5) The imbalance is within the specified limit.
* 6) Any rebalance would lead to ping-pong
*/
if (balance && !(*balance))
goto ret;
if (!sds.busiest || sds.busiest_nr_running == 0)
goto out_balanced;
if (sds.this_load >= sds.max_load)
goto out_balanced;
sds.avg_load = (SCHED_LOAD_SCALE * sds.total_load) / sds.total_pwr;
if (sds.this_load >= sds.avg_load)
goto out_balanced;
if (100 * sds.max_load <= sd->imbalance_pct * sds.this_load)
goto out_balanced;
sds.busiest_load_per_task /= sds.busiest_nr_running;
if (sds.group_imb)
sds.busiest_load_per_task =
min(sds.busiest_load_per_task, sds.avg_load);
/*
* We're trying to get all the cpus to the average_load, so we don't
* want to push ourselves above the average load, nor do we wish to
* reduce the max loaded cpu below the average load, as either of these
* actions would just result in more rebalancing later, and ping-pong
* tasks around. Thus we look for the minimum possible imbalance.
* Negative imbalances (*we* are more loaded than anyone else) will
* be counted as no imbalance for these purposes -- we can't fix that
* by pulling tasks to us. Be careful of negative numbers as they'll
* appear as very large values with unsigned longs.
*/
if (sds.max_load <= sds.busiest_load_per_task)
goto out_balanced;
/* Looks like there is an imbalance. Compute it */
calculate_imbalance(&sds, this_cpu, imbalance);
return sds.busiest;
out_balanced:
/*
* There is no obvious imbalance. But check if we can do some balancing
* to save power.
*/
if (check_power_save_busiest_group(&sds, this_cpu, imbalance))
return sds.busiest;
ret:
*imbalance = 0;
return NULL;
}
/*
* find_busiest_queue - find the busiest runqueue among the cpus in group.
*/
static struct rq *
find_busiest_queue(struct sched_group *group, enum cpu_idle_type idle,
unsigned long imbalance, const struct cpumask *cpus)
{
struct rq *busiest = NULL, *rq;
unsigned long max_load = 0;
int i;
for_each_cpu(i, sched_group_cpus(group)) {
unsigned long power = power_of(i);
unsigned long capacity = DIV_ROUND_CLOSEST(power, SCHED_LOAD_SCALE);
unsigned long wl;
if (!cpumask_test_cpu(i, cpus))
continue;
rq = cpu_rq(i);
wl = weighted_cpuload(i);
/*
* When comparing with imbalance, use weighted_cpuload()
* which is not scaled with the cpu power.
*/
if (capacity && rq->nr_running == 1 && wl > imbalance)
continue;
/*
* For the load comparisons with the other cpu's, consider
* the weighted_cpuload() scaled with the cpu power, so that
* the load can be moved away from the cpu that is potentially
* running at a lower capacity.
*/
wl = (wl * SCHED_LOAD_SCALE) / power;
if (wl > max_load) {
max_load = wl;
busiest = rq;
}
}
return busiest;
}
/*
* Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
* so long as it is large enough.
*/
#define MAX_PINNED_INTERVAL 512
/* Working cpumask for load_balance and load_balance_newidle. */
static DEFINE_PER_CPU(cpumask_var_t, load_balance_tmpmask);
/*
* Check this_cpu to ensure it is balanced within domain. Attempt to move
* tasks if there is an imbalance.
*/
static int load_balance(int this_cpu, struct rq *this_rq,
struct sched_domain *sd, enum cpu_idle_type idle,
int *balance)
{
int ld_moved, all_pinned = 0, active_balance = 0, sd_idle = 0;
struct sched_group *group;
unsigned long imbalance;
struct rq *busiest;
unsigned long flags;
struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
cpumask_copy(cpus, cpu_active_mask);
/*
* When power savings policy is enabled for the parent domain, idle
* sibling can pick up load irrespective of busy siblings. In this case,
* let the state of idle sibling percolate up as CPU_IDLE, instead of
* portraying it as CPU_NOT_IDLE.
*/
if (idle != CPU_NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER &&
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
sd_idle = 1;
schedstat_inc(sd, lb_count[idle]);
redo:
update_shares(sd);
group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle,
cpus, balance);
if (*balance == 0)
goto out_balanced;
if (!group) {
schedstat_inc(sd, lb_nobusyg[idle]);
goto out_balanced;
}
busiest = find_busiest_queue(group, idle, imbalance, cpus);
if (!busiest) {
schedstat_inc(sd, lb_nobusyq[idle]);
goto out_balanced;
}
BUG_ON(busiest == this_rq);
schedstat_add(sd, lb_imbalance[idle], imbalance);
ld_moved = 0;
if (busiest->nr_running > 1) {
/*
* Attempt to move tasks. If find_busiest_group has found
* an imbalance but busiest->nr_running <= 1, the group is
* still unbalanced. ld_moved simply stays zero, so it is
* correctly treated as an imbalance.
*/
local_irq_save(flags);
double_rq_lock(this_rq, busiest);
ld_moved = move_tasks(this_rq, this_cpu, busiest,
imbalance, sd, idle, &all_pinned);
double_rq_unlock(this_rq, busiest);
local_irq_restore(flags);
/*
* some other cpu did the load balance for us.
*/
if (ld_moved && this_cpu != smp_processor_id())
resched_cpu(this_cpu);
/* All tasks on this runqueue were pinned by CPU affinity */
if (unlikely(all_pinned)) {
cpumask_clear_cpu(cpu_of(busiest), cpus);
if (!cpumask_empty(cpus))
goto redo;
goto out_balanced;
}
}
if (!ld_moved) {
schedstat_inc(sd, lb_failed[idle]);
sd->nr_balance_failed++;
if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
raw_spin_lock_irqsave(&busiest->lock, flags);
/* don't kick the migration_thread, if the curr
* task on busiest cpu can't be moved to this_cpu
*/
if (!cpumask_test_cpu(this_cpu,
&busiest->curr->cpus_allowed)) {
raw_spin_unlock_irqrestore(&busiest->lock,
flags);
all_pinned = 1;
goto out_one_pinned;
}
if (!busiest->active_balance) {
busiest->active_balance = 1;
busiest->push_cpu = this_cpu;
active_balance = 1;
}
raw_spin_unlock_irqrestore(&busiest->lock, flags);
if (active_balance)
wake_up_process(busiest->migration_thread);
/*
* We've kicked active balancing, reset the failure
* counter.
*/
sd->nr_balance_failed = sd->cache_nice_tries+1;
}
} else
sd->nr_balance_failed = 0;
if (likely(!active_balance)) {
/* We were unbalanced, so reset the balancing interval */
sd->balance_interval = sd->min_interval;
} else {
/*
* If we've begun active balancing, start to back off. This
* case may not be covered by the all_pinned logic if there
* is only 1 task on the busy runqueue (because we don't call
* move_tasks).
*/
if (sd->balance_interval < sd->max_interval)
sd->balance_interval *= 2;
}
if (!ld_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
ld_moved = -1;
goto out;
out_balanced:
schedstat_inc(sd, lb_balanced[idle]);
sd->nr_balance_failed = 0;
out_one_pinned:
/* tune up the balancing interval */
if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) ||
(sd->balance_interval < sd->max_interval))
sd->balance_interval *= 2;
if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
ld_moved = -1;
else
ld_moved = 0;
out:
if (ld_moved)
update_shares(sd);
return ld_moved;
}
/*
* Check this_cpu to ensure it is balanced within domain. Attempt to move
* tasks if there is an imbalance.
*
* Called from schedule when this_rq is about to become idle (CPU_NEWLY_IDLE).
* this_rq is locked.
*/
static int
load_balance_newidle(int this_cpu, struct rq *this_rq, struct sched_domain *sd)
{
struct sched_group *group;
struct rq *busiest = NULL;
unsigned long imbalance;
int ld_moved = 0;
int sd_idle = 0;
int all_pinned = 0;
struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
cpumask_copy(cpus, cpu_active_mask);
/*
* When power savings policy is enabled for the parent domain, idle
* sibling can pick up load irrespective of busy siblings. In this case,
* let the state of idle sibling percolate up as IDLE, instead of
* portraying it as CPU_NOT_IDLE.
*/
if (sd->flags & SD_SHARE_CPUPOWER &&
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
sd_idle = 1;
schedstat_inc(sd, lb_count[CPU_NEWLY_IDLE]);
redo:
update_shares_locked(this_rq, sd);
group = find_busiest_group(sd, this_cpu, &imbalance, CPU_NEWLY_IDLE,
&sd_idle, cpus, NULL);
if (!group) {
schedstat_inc(sd, lb_nobusyg[CPU_NEWLY_IDLE]);
goto out_balanced;
}
busiest = find_busiest_queue(group, CPU_NEWLY_IDLE, imbalance, cpus);
if (!busiest) {
schedstat_inc(sd, lb_nobusyq[CPU_NEWLY_IDLE]);
goto out_balanced;
}
BUG_ON(busiest == this_rq);
schedstat_add(sd, lb_imbalance[CPU_NEWLY_IDLE], imbalance);
ld_moved = 0;
if (busiest->nr_running > 1) {
/* Attempt to move tasks */
double_lock_balance(this_rq, busiest);
/* this_rq->clock is already updated */
update_rq_clock(busiest);
ld_moved = move_tasks(this_rq, this_cpu, busiest,
imbalance, sd, CPU_NEWLY_IDLE,
&all_pinned);
double_unlock_balance(this_rq, busiest);
if (unlikely(all_pinned)) {
cpumask_clear_cpu(cpu_of(busiest), cpus);
if (!cpumask_empty(cpus))
goto redo;
}
}
if (!ld_moved) {
int active_balance = 0;
schedstat_inc(sd, lb_failed[CPU_NEWLY_IDLE]);
if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
return -1;
if (sched_mc_power_savings < POWERSAVINGS_BALANCE_WAKEUP)
return -1;
if (sd->nr_balance_failed++ < 2)
return -1;
/*
* The only task running in a non-idle cpu can be moved to this
* cpu in an attempt to completely freeup the other CPU
* package. The same method used to move task in load_balance()
* have been extended for load_balance_newidle() to speedup
* consolidation at sched_mc=POWERSAVINGS_BALANCE_WAKEUP (2)
*
* The package power saving logic comes from
* find_busiest_group(). If there are no imbalance, then
* f_b_g() will return NULL. However when sched_mc={1,2} then
* f_b_g() will select a group from which a running task may be
* pulled to this cpu in order to make the other package idle.
* If there is no opportunity to make a package idle and if
* there are no imbalance, then f_b_g() will return NULL and no
* action will be taken in load_balance_newidle().
*
* Under normal task pull operation due to imbalance, there
* will be more than one task in the source run queue and
* move_tasks() will succeed. ld_moved will be true and this
* active balance code will not be triggered.
*/
/* Lock busiest in correct order while this_rq is held */
double_lock_balance(this_rq, busiest);
/*
* don't kick the migration_thread, if the curr
* task on busiest cpu can't be moved to this_cpu
*/
if (!cpumask_test_cpu(this_cpu, &busiest->curr->cpus_allowed)) {
double_unlock_balance(this_rq, busiest);
all_pinned = 1;
return ld_moved;
}
if (!busiest->active_balance) {
busiest->active_balance = 1;
busiest->push_cpu = this_cpu;
active_balance = 1;
}
double_unlock_balance(this_rq, busiest);
/*
* Should not call ttwu while holding a rq->lock
*/
raw_spin_unlock(&this_rq->lock);
if (active_balance)
wake_up_process(busiest->migration_thread);
raw_spin_lock(&this_rq->lock);
} else
sd->nr_balance_failed = 0;
update_shares_locked(this_rq, sd);
return ld_moved;
out_balanced:
schedstat_inc(sd, lb_balanced[CPU_NEWLY_IDLE]);
if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
return -1;
sd->nr_balance_failed = 0;
return 0;
}
/*
* idle_balance is called by schedule() if this_cpu is about to become
* idle. Attempts to pull tasks from other CPUs.
*/
static void idle_balance(int this_cpu, struct rq *this_rq)
{
struct sched_domain *sd;
int pulled_task = 0;
unsigned long next_balance = jiffies + HZ;
this_rq->idle_stamp = this_rq->clock;
if (this_rq->avg_idle < sysctl_sched_migration_cost)
return;
for_each_domain(this_cpu, sd) {
unsigned long interval;
if (!(sd->flags & SD_LOAD_BALANCE))
continue;
if (sd->flags & SD_BALANCE_NEWIDLE)
/* If we've pulled tasks over stop searching: */
pulled_task = load_balance_newidle(this_cpu, this_rq,
sd);
interval = msecs_to_jiffies(sd->balance_interval);
if (time_after(next_balance, sd->last_balance + interval))
next_balance = sd->last_balance + interval;
if (pulled_task) {
this_rq->idle_stamp = 0;
break;
}
}
if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
/*
* We are going idle. next_balance may be set based on
* a busy processor. So reset next_balance.
*/
this_rq->next_balance = next_balance;
}
}
/*
* active_load_balance is run by migration threads. It pushes running tasks
* off the busiest CPU onto idle CPUs. It requires at least 1 task to be
* running on each physical CPU where possible, and avoids physical /
* logical imbalances.
*
* Called with busiest_rq locked.
*/
static void active_load_balance(struct rq *busiest_rq, int busiest_cpu)
{
int target_cpu = busiest_rq->push_cpu;
struct sched_domain *sd;
struct rq *target_rq;
/* Is there any task to move? */
if (busiest_rq->nr_running <= 1)
return;
target_rq = cpu_rq(target_cpu);
/*
* This condition is "impossible", if it occurs
* we need to fix it. Originally reported by
* Bjorn Helgaas on a 128-cpu setup.
*/
BUG_ON(busiest_rq == target_rq);
/* move a task from busiest_rq to target_rq */
double_lock_balance(busiest_rq, target_rq);
update_rq_clock(busiest_rq);
update_rq_clock(target_rq);
/* Search for an sd spanning us and the target CPU. */
for_each_domain(target_cpu, sd) {
if ((sd->flags & SD_LOAD_BALANCE) &&
cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
break;
}
if (likely(sd)) {
schedstat_inc(sd, alb_count);
if (move_one_task(target_rq, target_cpu, busiest_rq,
sd, CPU_IDLE))
schedstat_inc(sd, alb_pushed);
else
schedstat_inc(sd, alb_failed);
}
double_unlock_balance(busiest_rq, target_rq);
}
#ifdef CONFIG_NO_HZ
static struct {
atomic_t load_balancer;
cpumask_var_t cpu_mask;
cpumask_var_t ilb_grp_nohz_mask;
} nohz ____cacheline_aligned = {
.load_balancer = ATOMIC_INIT(-1),
};
int get_nohz_load_balancer(void)
{
return atomic_read(&nohz.load_balancer);
}
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
/**
* lowest_flag_domain - Return lowest sched_domain containing flag.
* @cpu: The cpu whose lowest level of sched domain is to
* be returned.
* @flag: The flag to check for the lowest sched_domain
* for the given cpu.
*
* Returns the lowest sched_domain of a cpu which contains the given flag.
*/
static inline struct sched_domain *lowest_flag_domain(int cpu, int flag)
{
struct sched_domain *sd;
for_each_domain(cpu, sd)
if (sd && (sd->flags & flag))
break;
return sd;
}
/**
* for_each_flag_domain - Iterates over sched_domains containing the flag.
* @cpu: The cpu whose domains we're iterating over.
* @sd: variable holding the value of the power_savings_sd
* for cpu.
* @flag: The flag to filter the sched_domains to be iterated.
*
* Iterates over all the scheduler domains for a given cpu that has the 'flag'
* set, starting from the lowest sched_domain to the highest.
*/
#define for_each_flag_domain(cpu, sd, flag) \
for (sd = lowest_flag_domain(cpu, flag); \
(sd && (sd->flags & flag)); sd = sd->parent)
/**
* is_semi_idle_group - Checks if the given sched_group is semi-idle.
* @ilb_group: group to be checked for semi-idleness
*
* Returns: 1 if the group is semi-idle. 0 otherwise.
*
* We define a sched_group to be semi idle if it has atleast one idle-CPU
* and atleast one non-idle CPU. This helper function checks if the given
* sched_group is semi-idle or not.
*/
static inline int is_semi_idle_group(struct sched_group *ilb_group)
{
cpumask_and(nohz.ilb_grp_nohz_mask, nohz.cpu_mask,
sched_group_cpus(ilb_group));
/*
* A sched_group is semi-idle when it has atleast one busy cpu
* and atleast one idle cpu.
*/
if (cpumask_empty(nohz.ilb_grp_nohz_mask))
return 0;
if (cpumask_equal(nohz.ilb_grp_nohz_mask, sched_group_cpus(ilb_group)))
return 0;
return 1;
return sum;
}
/**
* find_new_ilb - Finds the optimum idle load balancer for nomination.
* @cpu: The cpu which is nominating a new idle_load_balancer.
*
* Returns: Returns the id of the idle load balancer if it exists,
* Else, returns >= nr_cpu_ids.
*
* This algorithm picks the idle load balancer such that it belongs to a
* semi-idle powersavings sched_domain. The idea is to try and avoid
* completely idle packages/cores just for the purpose of idle load balancing
* when there are other idle cpu's which are better suited for that job.
*/
static int find_new_ilb(int cpu)
unsigned long nr_uninterruptible(void)
{
struct sched_domain *sd;
struct sched_group *ilb_group;
unsigned long i, sum = 0;
/*
* Have idle load balancer selection from semi-idle packages only
* when power-aware load balancing is enabled
*/
if (!(sched_smt_power_savings || sched_mc_power_savings))
goto out_done;
for_each_possible_cpu(i)
sum += cpu_rq(i)->nr_uninterruptible;
/*
* Optimize for the case when we have no idle CPUs or only one
* idle CPU. Don't walk the sched_domain hierarchy in such cases
* Since we read the counters lockless, it might be slightly
* inaccurate. Do not allow it to go below zero though:
*/
if (cpumask_weight(nohz.cpu_mask) < 2)
goto out_done;
for_each_flag_domain(cpu, sd, SD_POWERSAVINGS_BALANCE) {
ilb_group = sd->groups;
do {
if (is_semi_idle_group(ilb_group))
return cpumask_first(nohz.ilb_grp_nohz_mask);
ilb_group = ilb_group->next;
} while (ilb_group != sd->groups);
}
if (unlikely((long)sum < 0))
sum = 0;
out_done:
return cpumask_first(nohz.cpu_mask);
}
#else /* (CONFIG_SCHED_MC || CONFIG_SCHED_SMT) */
static inline int find_new_ilb(int call_cpu)
{
return cpumask_first(nohz.cpu_mask);
return sum;
}
#endif
/*
* This routine will try to nominate the ilb (idle load balancing)
* owner among the cpus whose ticks are stopped. ilb owner will do the idle
* load balancing on behalf of all those cpus. If all the cpus in the system
* go into this tickless mode, then there will be no ilb owner (as there is
* no need for one) and all the cpus will sleep till the next wakeup event
* arrives...
*
* For the ilb owner, tick is not stopped. And this tick will be used
* for idle load balancing. ilb owner will still be part of
* nohz.cpu_mask..
*
* While stopping the tick, this cpu will become the ilb owner if there
* is no other owner. And will be the owner till that cpu becomes busy
* or if all cpus in the system stop their ticks at which point
* there is no need for ilb owner.
*
* When the ilb owner becomes busy, it nominates another owner, during the
* next busy scheduler_tick()
*/
int select_nohz_load_balancer(int stop_tick)
unsigned long long nr_context_switches(void)
{
int cpu = smp_processor_id();
int i;
unsigned long long sum = 0;
if (stop_tick) {
cpu_rq(cpu)->in_nohz_recently = 1;
for_each_possible_cpu(i)
sum += cpu_rq(i)->nr_switches;
if (!cpu_active(cpu)) {
if (atomic_read(&nohz.load_balancer) != cpu)
return 0;
return sum;
}
/*
* If we are going offline and still the leader,
* give up!
*/
if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
BUG();
unsigned long nr_iowait(void)
{
unsigned long i, sum = 0;
return 0;
}
for_each_possible_cpu(i)
sum += atomic_read(&cpu_rq(i)->nr_iowait);
cpumask_set_cpu(cpu, nohz.cpu_mask);
return sum;
}
/* time for ilb owner also to sleep */
if (cpumask_weight(nohz.cpu_mask) == num_active_cpus()) {
if (atomic_read(&nohz.load_balancer) == cpu)
atomic_set(&nohz.load_balancer, -1);
return 0;
}
unsigned long nr_iowait_cpu(void)
{
struct rq *this = this_rq();
return atomic_read(&this->nr_iowait);
}
if (atomic_read(&nohz.load_balancer) == -1) {
/* make me the ilb owner */
if (atomic_cmpxchg(&nohz.load_balancer, -1, cpu) == -1)
return 1;
} else if (atomic_read(&nohz.load_balancer) == cpu) {
int new_ilb;
unsigned long this_cpu_load(void)
{
struct rq *this = this_rq();
return this->cpu_load[0];
}
if (!(sched_smt_power_savings ||
sched_mc_power_savings))
return 1;
/*
* Check to see if there is a more power-efficient
* ilb.
*/
new_ilb = find_new_ilb(cpu);
if (new_ilb < nr_cpu_ids && new_ilb != cpu) {
atomic_set(&nohz.load_balancer, -1);
resched_cpu(new_ilb);
return 0;
}
return 1;
}
} else {
if (!cpumask_test_cpu(cpu, nohz.cpu_mask))
return 0;
cpumask_clear_cpu(cpu, nohz.cpu_mask);
/* Variables and functions for calc_load */
static atomic_long_t calc_load_tasks;
static unsigned long calc_load_update;
unsigned long avenrun[3];
EXPORT_SYMBOL(avenrun);
if (atomic_read(&nohz.load_balancer) == cpu)
if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
BUG();
}
return 0;
/**
* get_avenrun - get the load average array
* @loads: pointer to dest load array
* @offset: offset to add
* @shift: shift count to shift the result left
*
* These values are estimates at best, so no need for locking.
*/
void get_avenrun(unsigned long *loads, unsigned long offset, int shift)
{
loads[0] = (avenrun[0] + offset) << shift;
loads[1] = (avenrun[1] + offset) << shift;
loads[2] = (avenrun[2] + offset) << shift;
}
#endif
static DEFINE_SPINLOCK(balancing);
static unsigned long
calc_load(unsigned long load, unsigned long exp, unsigned long active)
{
load *= exp;
load += active * (FIXED_1 - exp);
return load >> FSHIFT;
}
/*
* It checks each scheduling domain to see if it is due to be balanced,
* and initiates a balancing operation if so.
*
* Balancing parameters are set up in arch_init_sched_domains.
* calc_load - update the avenrun load estimates 10 ticks after the
* CPUs have updated calc_load_tasks.
*/
static void rebalance_domains(int cpu, enum cpu_idle_type idle)
void calc_global_load(void)
{
int balance = 1;
struct rq *rq = cpu_rq(cpu);
unsigned long interval;
struct sched_domain *sd;
/* Earliest time when we have to do rebalance again */
unsigned long next_balance = jiffies + 60*HZ;
int update_next_balance = 0;
int need_serialize;
unsigned long upd = calc_load_update + 10;
long active;
for_each_domain(cpu, sd) {
if (!(sd->flags & SD_LOAD_BALANCE))
continue;
if (time_before(jiffies, upd))
return;
interval = sd->balance_interval;
if (idle != CPU_IDLE)
interval *= sd->busy_factor;
active = atomic_long_read(&calc_load_tasks);
active = active > 0 ? active * FIXED_1 : 0;
/* scale ms to jiffies */
interval = msecs_to_jiffies(interval);
if (unlikely(!interval))
interval = 1;
if (interval > HZ*NR_CPUS/10)
interval = HZ*NR_CPUS/10;
avenrun[0] = calc_load(avenrun[0], EXP_1, active);
avenrun[1] = calc_load(avenrun[1], EXP_5, active);
avenrun[2] = calc_load(avenrun[2], EXP_15, active);
need_serialize = sd->flags & SD_SERIALIZE;
calc_load_update += LOAD_FREQ;
}
if (need_serialize) {
if (!spin_trylock(&balancing))
goto out;
}
/*
* Either called from update_cpu_load() or from a cpu going idle
*/
static void calc_load_account_active(struct rq *this_rq)
{
long nr_active, delta;
if (time_after_eq(jiffies, sd->last_balance + interval)) {
if (load_balance(cpu, rq, sd, idle, &balance)) {
/*
* We've pulled tasks over so either we're no
* longer idle, or one of our SMT siblings is
* not idle.
*/
idle = CPU_NOT_IDLE;
}
sd->last_balance = jiffies;
}
if (need_serialize)
spin_unlock(&balancing);
out:
if (time_after(next_balance, sd->last_balance + interval)) {
next_balance = sd->last_balance + interval;
update_next_balance = 1;
}
nr_active = this_rq->nr_running;
nr_active += (long) this_rq->nr_uninterruptible;
/*
* Stop the load balance at this level. There is another
* CPU in our sched group which is doing load balancing more
* actively.
*/
if (!balance)
break;
if (nr_active != this_rq->calc_load_active) {
delta = nr_active - this_rq->calc_load_active;
this_rq->calc_load_active = nr_active;
atomic_long_add(delta, &calc_load_tasks);
}
/*
* next_balance will be updated only when there is a need.
* When the cpu is attached to null domain for ex, it will not be
* updated.
*/
if (likely(update_next_balance))
rq->next_balance = next_balance;
}
/*
* run_rebalance_domains is triggered when needed from the scheduler tick.
* In CONFIG_NO_HZ case, the idle load balance owner will do the
* rebalancing for all the cpus for whom scheduler ticks are stopped.
* Update rq->cpu_load[] statistics. This function is usually called every
* scheduler tick (TICK_NSEC).
*/
static void run_rebalance_domains(struct softirq_action *h)
static void update_cpu_load(struct rq *this_rq)
{
int this_cpu = smp_processor_id();
struct rq *this_rq = cpu_rq(this_cpu);
enum cpu_idle_type idle = this_rq->idle_at_tick ?
CPU_IDLE : CPU_NOT_IDLE;
rebalance_domains(this_cpu, idle);
unsigned long this_load = this_rq->load.weight;
int i, scale;
#ifdef CONFIG_NO_HZ
/*
* If this cpu is the owner for idle load balancing, then do the
* balancing on behalf of the other idle cpus whose ticks are
* stopped.
*/
if (this_rq->idle_at_tick &&
atomic_read(&nohz.load_balancer) == this_cpu) {
struct rq *rq;
int balance_cpu;
this_rq->nr_load_updates++;
for_each_cpu(balance_cpu, nohz.cpu_mask) {
if (balance_cpu == this_cpu)
continue;
/* Update our load: */
for (i = 0, scale = 1; i < CPU_LOAD_IDX_MAX; i++, scale += scale) {
unsigned long old_load, new_load;
/*
* If this cpu gets work to do, stop the load balancing
* work being done for other cpus. Next load
* balancing owner will pick it up.
*/
if (need_resched())
break;
/* scale is effectively 1 << i now, and >> i divides by scale */
rebalance_domains(balance_cpu, CPU_IDLE);
old_load = this_rq->cpu_load[i];
new_load = this_load;
/*
* Round up the averaging division if load is increasing. This
* prevents us from getting stuck on 9 if the load is 10, for
* example.
*/
if (new_load > old_load)
new_load += scale-1;
this_rq->cpu_load[i] = (old_load*(scale-1) + new_load) >> i;
}
rq = cpu_rq(balance_cpu);
if (time_after(this_rq->next_balance, rq->next_balance))
this_rq->next_balance = rq->next_balance;
}
if (time_after_eq(jiffies, this_rq->calc_load_update)) {
this_rq->calc_load_update += LOAD_FREQ;
calc_load_account_active(this_rq);
}
#endif
}
static inline int on_null_domain(int cpu)
{
return !rcu_dereference_sched(cpu_rq(cpu)->sd);
}
#ifdef CONFIG_SMP
/*
* Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
*
* In case of CONFIG_NO_HZ, this is the place where we nominate a new
* idle load balancing owner or decide to stop the periodic load balancing,
* if the whole system is idle.
* sched_exec - execve() is a valuable balancing opportunity, because at
* this point the task has the smallest effective memory and cache footprint.
*/
static inline void trigger_load_balance(struct rq *rq, int cpu)
void sched_exec(void)
{
#ifdef CONFIG_NO_HZ
/*
* If we were in the nohz mode recently and busy at the current
* scheduler tick, then check if we need to nominate new idle
* load balancer.
*/
if (rq->in_nohz_recently && !rq->idle_at_tick) {
rq->in_nohz_recently = 0;
if (atomic_read(&nohz.load_balancer) == cpu) {
cpumask_clear_cpu(cpu, nohz.cpu_mask);
atomic_set(&nohz.load_balancer, -1);
}
if (atomic_read(&nohz.load_balancer) == -1) {
int ilb = find_new_ilb(cpu);
struct task_struct *p = current;
struct migration_req req;
int dest_cpu, this_cpu;
unsigned long flags;
struct rq *rq;
if (ilb < nr_cpu_ids)
resched_cpu(ilb);
}
again:
this_cpu = get_cpu();
dest_cpu = select_task_rq(p, SD_BALANCE_EXEC, 0);
if (dest_cpu == this_cpu) {
put_cpu();
return;
}
rq = task_rq_lock(p, &flags);
put_cpu();
/*
* If this cpu is idle and doing idle load balancing for all the
* cpus with ticks stopped, is it time for that to stop?
* select_task_rq() can race against ->cpus_allowed
*/
if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) == cpu &&
cpumask_weight(nohz.cpu_mask) == num_online_cpus()) {
resched_cpu(cpu);
return;
if (!cpumask_test_cpu(dest_cpu, &p->cpus_allowed)
|| unlikely(!cpu_active(dest_cpu))) {
task_rq_unlock(rq, &flags);
goto again;
}
/*
* If this cpu is idle and the idle load balancing is done by
* someone else, then no need raise the SCHED_SOFTIRQ
*/
if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) != cpu &&
cpumask_test_cpu(cpu, nohz.cpu_mask))
return;
#endif
/* Don't need to rebalance while attached to NULL domain */
if (time_after_eq(jiffies, rq->next_balance) &&
likely(!on_null_domain(cpu)))
raise_softirq(SCHED_SOFTIRQ);
}
/* force the process onto the specified CPU */
if (migrate_task(p, dest_cpu, &req)) {
/* Need to wait for migration thread (might exit: take ref). */
struct task_struct *mt = rq->migration_thread;
#else /* CONFIG_SMP */
get_task_struct(mt);
task_rq_unlock(rq, &flags);
wake_up_process(mt);
put_task_struct(mt);
wait_for_completion(&req.done);
/*
* on UP we do not need to balance between CPUs:
*/
static inline void idle_balance(int cpu, struct rq *rq)
{
return;
}
task_rq_unlock(rq, &flags);
}
#endif
......@@ -6114,7 +4260,7 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
unsigned long flags;
int oldprio, on_rq, running;
struct rq *rq;
const struct sched_class *prev_class = p->sched_class;
const struct sched_class *prev_class;
BUG_ON(prio < 0 || prio > MAX_PRIO);
......@@ -6122,6 +4268,7 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
update_rq_clock(rq);
oldprio = p->prio;
prev_class = p->sched_class;
on_rq = p->se.on_rq;
running = task_current(rq, p);
if (on_rq)
......@@ -6139,7 +4286,7 @@ void rt_mutex_setprio(struct task_struct *p, int prio)
if (running)
p->sched_class->set_curr_task(rq);
if (on_rq) {
enqueue_task(rq, p, 0);
enqueue_task(rq, p, 0, oldprio < prio);
check_class_changed(rq, p, prev_class, oldprio, running);
}
......@@ -6183,7 +4330,7 @@ void set_user_nice(struct task_struct *p, long nice)
delta = p->prio - old_prio;
if (on_rq) {
enqueue_task(rq, p, 0);
enqueue_task(rq, p, 0, false);
/*
* If the task increased its priority or is running and
* lowered its priority, then reschedule its CPU:
......@@ -6341,7 +4488,7 @@ static int __sched_setscheduler(struct task_struct *p, int policy,
{
int retval, oldprio, oldpolicy = -1, on_rq, running;
unsigned long flags;
const struct sched_class *prev_class = p->sched_class;
const struct sched_class *prev_class;
struct rq *rq;
int reset_on_fork;
......@@ -6455,6 +4602,7 @@ static int __sched_setscheduler(struct task_struct *p, int policy,
p->sched_reset_on_fork = reset_on_fork;
oldprio = p->prio;
prev_class = p->sched_class;
__setscheduler(rq, p, policy, param->sched_priority);
if (running)
......@@ -9493,7 +7641,6 @@ static void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
tg->rt_rq[cpu] = rt_rq;
init_rt_rq(rt_rq, rq);
rt_rq->tg = tg;
rt_rq->rt_se = rt_se;
rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
if (add)
list_add(&rt_rq->leaf_rt_rq_list, &rq->leaf_rt_rq_list);
......@@ -9524,9 +7671,6 @@ void __init sched_init(void)
#ifdef CONFIG_RT_GROUP_SCHED
alloc_size += 2 * nr_cpu_ids * sizeof(void **);
#endif
#ifdef CONFIG_USER_SCHED
alloc_size *= 2;
#endif
#ifdef CONFIG_CPUMASK_OFFSTACK
alloc_size += num_possible_cpus() * cpumask_size();
#endif
......@@ -9540,13 +7684,6 @@ void __init sched_init(void)
init_task_group.cfs_rq = (struct cfs_rq **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
#ifdef CONFIG_USER_SCHED
root_task_group.se = (struct sched_entity **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
root_task_group.cfs_rq = (struct cfs_rq **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
#endif /* CONFIG_USER_SCHED */
#endif /* CONFIG_FAIR_GROUP_SCHED */
#ifdef CONFIG_RT_GROUP_SCHED
init_task_group.rt_se = (struct sched_rt_entity **)ptr;
......@@ -9555,13 +7692,6 @@ void __init sched_init(void)
init_task_group.rt_rq = (struct rt_rq **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
#ifdef CONFIG_USER_SCHED
root_task_group.rt_se = (struct sched_rt_entity **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
root_task_group.rt_rq = (struct rt_rq **)ptr;
ptr += nr_cpu_ids * sizeof(void **);
#endif /* CONFIG_USER_SCHED */
#endif /* CONFIG_RT_GROUP_SCHED */
#ifdef CONFIG_CPUMASK_OFFSTACK
for_each_possible_cpu(i) {
......@@ -9581,22 +7711,13 @@ void __init sched_init(void)
#ifdef CONFIG_RT_GROUP_SCHED
init_rt_bandwidth(&init_task_group.rt_bandwidth,
global_rt_period(), global_rt_runtime());
#ifdef CONFIG_USER_SCHED
init_rt_bandwidth(&root_task_group.rt_bandwidth,
global_rt_period(), RUNTIME_INF);
#endif /* CONFIG_USER_SCHED */
#endif /* CONFIG_RT_GROUP_SCHED */
#ifdef CONFIG_GROUP_SCHED
#ifdef CONFIG_CGROUP_SCHED
list_add(&init_task_group.list, &task_groups);
INIT_LIST_HEAD(&init_task_group.children);
#ifdef CONFIG_USER_SCHED
INIT_LIST_HEAD(&root_task_group.children);
init_task_group.parent = &root_task_group;
list_add(&init_task_group.siblings, &root_task_group.children);
#endif /* CONFIG_USER_SCHED */
#endif /* CONFIG_GROUP_SCHED */
#endif /* CONFIG_CGROUP_SCHED */
#if defined CONFIG_FAIR_GROUP_SCHED && defined CONFIG_SMP
update_shares_data = __alloc_percpu(nr_cpu_ids * sizeof(unsigned long),
......@@ -9636,25 +7757,6 @@ void __init sched_init(void)
* directly in rq->cfs (i.e init_task_group->se[] = NULL).
*/
init_tg_cfs_entry(&init_task_group, &rq->cfs, NULL, i, 1, NULL);
#elif defined CONFIG_USER_SCHED
root_task_group.shares = NICE_0_LOAD;
init_tg_cfs_entry(&root_task_group, &rq->cfs, NULL, i, 0, NULL);
/*
* In case of task-groups formed thr' the user id of tasks,
* init_task_group represents tasks belonging to root user.
* Hence it forms a sibling of all subsequent groups formed.
* In this case, init_task_group gets only a fraction of overall
* system cpu resource, based on the weight assigned to root
* user's cpu share (INIT_TASK_GROUP_LOAD). This is accomplished
* by letting tasks of init_task_group sit in a separate cfs_rq
* (init_tg_cfs_rq) and having one entity represent this group of
* tasks in rq->cfs (i.e init_task_group->se[] != NULL).
*/
init_tg_cfs_entry(&init_task_group,
&per_cpu(init_tg_cfs_rq, i),
&per_cpu(init_sched_entity, i), i, 1,
root_task_group.se[i]);
#endif
#endif /* CONFIG_FAIR_GROUP_SCHED */
......@@ -9663,12 +7765,6 @@ void __init sched_init(void)
INIT_LIST_HEAD(&rq->leaf_rt_rq_list);
#ifdef CONFIG_CGROUP_SCHED
init_tg_rt_entry(&init_task_group, &rq->rt, NULL, i, 1, NULL);
#elif defined CONFIG_USER_SCHED
init_tg_rt_entry(&root_task_group, &rq->rt, NULL, i, 0, NULL);
init_tg_rt_entry(&init_task_group,
&per_cpu(init_rt_rq_var, i),
&per_cpu(init_sched_rt_entity, i), i, 1,
root_task_group.rt_se[i]);
#endif
#endif
......@@ -9753,7 +7849,7 @@ static inline int preempt_count_equals(int preempt_offset)
return (nested == PREEMPT_INATOMIC_BASE + preempt_offset);
}
void __might_sleep(char *file, int line, int preempt_offset)
void __might_sleep(const char *file, int line, int preempt_offset)
{
#ifdef in_atomic
static unsigned long prev_jiffy; /* ratelimiting */
......@@ -10064,7 +8160,7 @@ static inline void unregister_rt_sched_group(struct task_group *tg, int cpu)
}
#endif /* CONFIG_RT_GROUP_SCHED */
#ifdef CONFIG_GROUP_SCHED
#ifdef CONFIG_CGROUP_SCHED
static void free_sched_group(struct task_group *tg)
{
free_fair_sched_group(tg);
......@@ -10169,11 +8265,11 @@ void sched_move_task(struct task_struct *tsk)
if (unlikely(running))
tsk->sched_class->set_curr_task(rq);
if (on_rq)
enqueue_task(rq, tsk, 0);
enqueue_task(rq, tsk, 0, false);
task_rq_unlock(rq, &flags);
}
#endif /* CONFIG_GROUP_SCHED */
#endif /* CONFIG_CGROUP_SCHED */
#ifdef CONFIG_FAIR_GROUP_SCHED
static void __set_se_shares(struct sched_entity *se, unsigned long shares)
......@@ -10315,13 +8411,6 @@ static int tg_schedulable(struct task_group *tg, void *data)
runtime = d->rt_runtime;
}
#ifdef CONFIG_USER_SCHED
if (tg == &root_task_group) {
period = global_rt_period();
runtime = global_rt_runtime();
}
#endif
/*
* Cannot have more runtime than the period.
*/
......@@ -10940,6 +9029,23 @@ static void cpuacct_charge(struct task_struct *tsk, u64 cputime)
rcu_read_unlock();
}
/*
* When CONFIG_VIRT_CPU_ACCOUNTING is enabled one jiffy can be very large
* in cputime_t units. As a result, cpuacct_update_stats calls
* percpu_counter_add with values large enough to always overflow the
* per cpu batch limit causing bad SMP scalability.
*
* To fix this we scale percpu_counter_batch by cputime_one_jiffy so we
* batch the same amount of time with CONFIG_VIRT_CPU_ACCOUNTING disabled
* and enabled. We cap it at INT_MAX which is the largest allowed batch value.
*/
#ifdef CONFIG_SMP
#define CPUACCT_BATCH \
min_t(long, percpu_counter_batch * cputime_one_jiffy, INT_MAX)
#else
#define CPUACCT_BATCH 0
#endif
/*
* Charge the system/user time to the task's accounting group.
*/
......@@ -10947,6 +9053,7 @@ static void cpuacct_update_stats(struct task_struct *tsk,
enum cpuacct_stat_index idx, cputime_t val)
{
struct cpuacct *ca;
int batch = CPUACCT_BATCH;
if (unlikely(!cpuacct_subsys.active))
return;
......@@ -10955,7 +9062,7 @@ static void cpuacct_update_stats(struct task_struct *tsk,
ca = task_ca(tsk);
do {
percpu_counter_add(&ca->cpustat[idx], val);
__percpu_counter_add(&ca->cpustat[idx], val, batch);
ca = ca->parent;
} while (ca);
rcu_read_unlock();
......
kernel/sched_cpupri.c
View file @ f66ffded
......@@ -47,9 +47,7 @@ static int convert_prio(int prio)
}
#define for_each_cpupri_active(array, idx) \
for (idx = find_first_bit(array, CPUPRI_NR_PRIORITIES); \
idx < CPUPRI_NR_PRIORITIES; \
idx = find_next_bit(array, CPUPRI_NR_PRIORITIES, idx+1))
for_each_bit(idx, array, CPUPRI_NR_PRIORITIES)
/**
* cpupri_find - find the best (lowest-pri) CPU in the system
......
kernel/sched_fair.c
View file @ f66ffded
......@@ -1053,7 +1053,8 @@ static inline void hrtick_update(struct rq *rq)
* increased. Here we update the fair scheduling stats and
* then put the task into the rbtree:
*/
static void enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup)
static void
enqueue_task_fair(struct rq *rq, struct task_struct *p, int wakeup, bool head)
{
struct cfs_rq *cfs_rq;
struct sched_entity *se = &p->se;
......@@ -1815,57 +1816,164 @@ static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
*/
/*
* Load-balancing iterator. Note: while the runqueue stays locked
* during the whole iteration, the current task might be
* dequeued so the iterator has to be dequeue-safe. Here we
* achieve that by always pre-iterating before returning
* the current task:
* pull_task - move a task from a remote runqueue to the local runqueue.
* Both runqueues must be locked.
*/
static struct task_struct *
__load_balance_iterator(struct cfs_rq *cfs_rq, struct list_head *next)
static void pull_task(struct rq *src_rq, struct task_struct *p,
struct rq *this_rq, int this_cpu)
{
struct task_struct *p = NULL;
struct sched_entity *se;
deactivate_task(src_rq, p, 0);
set_task_cpu(p, this_cpu);
activate_task(this_rq, p, 0);
check_preempt_curr(this_rq, p, 0);
}
if (next == &cfs_rq->tasks)
return NULL;
/*
* can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
*/
static
int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
struct sched_domain *sd, enum cpu_idle_type idle,
int *all_pinned)
{
int tsk_cache_hot = 0;
/*
* We do not migrate tasks that are:
* 1) running (obviously), or
* 2) cannot be migrated to this CPU due to cpus_allowed, or
* 3) are cache-hot on their current CPU.
*/
if (!cpumask_test_cpu(this_cpu, &p->cpus_allowed)) {
schedstat_inc(p, se.nr_failed_migrations_affine);
return 0;
}
*all_pinned = 0;
se = list_entry(next, struct sched_entity, group_node);
p = task_of(se);
cfs_rq->balance_iterator = next->next;
if (task_running(rq, p)) {
schedstat_inc(p, se.nr_failed_migrations_running);
return 0;
}
return p;
}
/*
* Aggressive migration if:
* 1) task is cache cold, or
* 2) too many balance attempts have failed.
*/
static struct task_struct *load_balance_start_fair(void *arg)
{
struct cfs_rq *cfs_rq = arg;
tsk_cache_hot = task_hot(p, rq->clock, sd);
if (!tsk_cache_hot ||
sd->nr_balance_failed > sd->cache_nice_tries) {
#ifdef CONFIG_SCHEDSTATS
if (tsk_cache_hot) {
schedstat_inc(sd, lb_hot_gained[idle]);
schedstat_inc(p, se.nr_forced_migrations);
}
#endif
return 1;
}
return __load_balance_iterator(cfs_rq, cfs_rq->tasks.next);
if (tsk_cache_hot) {
schedstat_inc(p, se.nr_failed_migrations_hot);
return 0;
}
return 1;
}
static struct task_struct *load_balance_next_fair(void *arg)
/*
* move_one_task tries to move exactly one task from busiest to this_rq, as
* part of active balancing operations within "domain".
* Returns 1 if successful and 0 otherwise.
*
* Called with both runqueues locked.
*/
static int
move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest,
struct sched_domain *sd, enum cpu_idle_type idle)
{
struct cfs_rq *cfs_rq = arg;
struct task_struct *p, *n;
struct cfs_rq *cfs_rq;
int pinned = 0;
for_each_leaf_cfs_rq(busiest, cfs_rq) {
list_for_each_entry_safe(p, n, &cfs_rq->tasks, se.group_node) {
if (!can_migrate_task(p, busiest, this_cpu,
sd, idle, &pinned))
continue;
pull_task(busiest, p, this_rq, this_cpu);
/*
* Right now, this is only the second place pull_task()
* is called, so we can safely collect pull_task()
* stats here rather than inside pull_task().
*/
schedstat_inc(sd, lb_gained[idle]);
return 1;
}
}
return __load_balance_iterator(cfs_rq, cfs_rq->balance_iterator);
return 0;
}
static unsigned long
__load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
unsigned long max_load_move, struct sched_domain *sd,
enum cpu_idle_type idle, int *all_pinned, int *this_best_prio,
struct cfs_rq *cfs_rq)
balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
unsigned long max_load_move, struct sched_domain *sd,
enum cpu_idle_type idle, int *all_pinned,
int *this_best_prio, struct cfs_rq *busiest_cfs_rq)
{
struct rq_iterator cfs_rq_iterator;
int loops = 0, pulled = 0, pinned = 0;
long rem_load_move = max_load_move;
struct task_struct *p, *n;
cfs_rq_iterator.start = load_balance_start_fair;
cfs_rq_iterator.next = load_balance_next_fair;
cfs_rq_iterator.arg = cfs_rq;
if (max_load_move == 0)
goto out;
return balance_tasks(this_rq, this_cpu, busiest,
max_load_move, sd, idle, all_pinned,
this_best_prio, &cfs_rq_iterator);
pinned = 1;
list_for_each_entry_safe(p, n, &busiest_cfs_rq->tasks, se.group_node) {
if (loops++ > sysctl_sched_nr_migrate)
break;
if ((p->se.load.weight >> 1) > rem_load_move ||
!can_migrate_task(p, busiest, this_cpu, sd, idle, &pinned))
continue;
pull_task(busiest, p, this_rq, this_cpu);
pulled++;
rem_load_move -= p->se.load.weight;
#ifdef CONFIG_PREEMPT
/*
* NEWIDLE balancing is a source of latency, so preemptible
* kernels will stop after the first task is pulled to minimize
* the critical section.
*/
if (idle == CPU_NEWLY_IDLE)
break;
#endif
/*
* We only want to steal up to the prescribed amount of
* weighted load.
*/
if (rem_load_move <= 0)
break;
if (p->prio < *this_best_prio)
*this_best_prio = p->prio;
}
out:
/*
* Right now, this is one of only two places pull_task() is called,
* so we can safely collect pull_task() stats here rather than
* inside pull_task().
*/
schedstat_add(sd, lb_gained[idle], pulled);
if (all_pinned)
*all_pinned = pinned;
return max_load_move - rem_load_move;
}
#ifdef CONFIG_FAIR_GROUP_SCHED
......@@ -1897,9 +2005,9 @@ load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
rem_load = (u64)rem_load_move * busiest_weight;
rem_load = div_u64(rem_load, busiest_h_load + 1);
moved_load = __load_balance_fair(this_rq, this_cpu, busiest,
moved_load = balance_tasks(this_rq, this_cpu, busiest,
rem_load, sd, idle, all_pinned, this_best_prio,
tg->cfs_rq[busiest_cpu]);
busiest_cfs_rq);
if (!moved_load)
continue;
......@@ -1922,44 +2030,1527 @@ load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
struct sched_domain *sd, enum cpu_idle_type idle,
int *all_pinned, int *this_best_prio)
{
return __load_balance_fair(this_rq, this_cpu, busiest,
return balance_tasks(this_rq, this_cpu, busiest,
max_load_move, sd, idle, all_pinned,
this_best_prio, &busiest->cfs);
}
#endif
static int
move_one_task_fair(struct rq *this_rq, int this_cpu, struct rq *busiest,
struct sched_domain *sd, enum cpu_idle_type idle)
/*
* move_tasks tries to move up to max_load_move weighted load from busiest to
* this_rq, as part of a balancing operation within domain "sd".
* Returns 1 if successful and 0 otherwise.
*
* Called with both runqueues locked.
*/
static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest,
unsigned long max_load_move,
struct sched_domain *sd, enum cpu_idle_type idle,
int *all_pinned)
{
struct cfs_rq *busy_cfs_rq;
struct rq_iterator cfs_rq_iterator;
unsigned long total_load_moved = 0, load_moved;
int this_best_prio = this_rq->curr->prio;
do {
load_moved = load_balance_fair(this_rq, this_cpu, busiest,
max_load_move - total_load_moved,
sd, idle, all_pinned, &this_best_prio);
cfs_rq_iterator.start = load_balance_start_fair;
cfs_rq_iterator.next = load_balance_next_fair;
total_load_moved += load_moved;
for_each_leaf_cfs_rq(busiest, busy_cfs_rq) {
#ifdef CONFIG_PREEMPT
/*
* pass busy_cfs_rq argument into
* load_balance_[start|next]_fair iterators
* NEWIDLE balancing is a source of latency, so preemptible
* kernels will stop after the first task is pulled to minimize
* the critical section.
*/
cfs_rq_iterator.arg = busy_cfs_rq;
if (iter_move_one_task(this_rq, this_cpu, busiest, sd, idle,
&cfs_rq_iterator))
return 1;
if (idle == CPU_NEWLY_IDLE && this_rq->nr_running)
break;
if (raw_spin_is_contended(&this_rq->lock) ||
raw_spin_is_contended(&busiest->lock))
break;
#endif
} while (load_moved && max_load_move > total_load_moved);
return total_load_moved > 0;
}
/********** Helpers for find_busiest_group ************************/
/*
* sd_lb_stats - Structure to store the statistics of a sched_domain
* during load balancing.
*/
struct sd_lb_stats {
struct sched_group *busiest; /* Busiest group in this sd */
struct sched_group *this; /* Local group in this sd */
unsigned long total_load; /* Total load of all groups in sd */
unsigned long total_pwr; /* Total power of all groups in sd */
unsigned long avg_load; /* Average load across all groups in sd */
/** Statistics of this group */
unsigned long this_load;
unsigned long this_load_per_task;
unsigned long this_nr_running;
/* Statistics of the busiest group */
unsigned long max_load;
unsigned long busiest_load_per_task;
unsigned long busiest_nr_running;
unsigned long busiest_group_capacity;
int group_imb; /* Is there imbalance in this sd */
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
int power_savings_balance; /* Is powersave balance needed for this sd */
struct sched_group *group_min; /* Least loaded group in sd */
struct sched_group *group_leader; /* Group which relieves group_min */
unsigned long min_load_per_task; /* load_per_task in group_min */
unsigned long leader_nr_running; /* Nr running of group_leader */
unsigned long min_nr_running; /* Nr running of group_min */
#endif
};
/*
* sg_lb_stats - stats of a sched_group required for load_balancing
*/
struct sg_lb_stats {
unsigned long avg_load; /*Avg load across the CPUs of the group */
unsigned long group_load; /* Total load over the CPUs of the group */
unsigned long sum_nr_running; /* Nr tasks running in the group */
unsigned long sum_weighted_load; /* Weighted load of group's tasks */
unsigned long group_capacity;
int group_imb; /* Is there an imbalance in the group ? */
};
/**
* group_first_cpu - Returns the first cpu in the cpumask of a sched_group.
* @group: The group whose first cpu is to be returned.
*/
static inline unsigned int group_first_cpu(struct sched_group *group)
{
return cpumask_first(sched_group_cpus(group));
}
/**
* get_sd_load_idx - Obtain the load index for a given sched domain.
* @sd: The sched_domain whose load_idx is to be obtained.
* @idle: The Idle status of the CPU for whose sd load_icx is obtained.
*/
static inline int get_sd_load_idx(struct sched_domain *sd,
enum cpu_idle_type idle)
{
int load_idx;
switch (idle) {
case CPU_NOT_IDLE:
load_idx = sd->busy_idx;
break;
case CPU_NEWLY_IDLE:
load_idx = sd->newidle_idx;
break;
default:
load_idx = sd->idle_idx;
break;
}
return load_idx;
}
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
/**
* init_sd_power_savings_stats - Initialize power savings statistics for
* the given sched_domain, during load balancing.
*
* @sd: Sched domain whose power-savings statistics are to be initialized.
* @sds: Variable containing the statistics for sd.
* @idle: Idle status of the CPU at which we're performing load-balancing.
*/
static inline void init_sd_power_savings_stats(struct sched_domain *sd,
struct sd_lb_stats *sds, enum cpu_idle_type idle)
{
/*
* Busy processors will not participate in power savings
* balance.
*/
if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE))
sds->power_savings_balance = 0;
else {
sds->power_savings_balance = 1;
sds->min_nr_running = ULONG_MAX;
sds->leader_nr_running = 0;
}
}
/**
* update_sd_power_savings_stats - Update the power saving stats for a
* sched_domain while performing load balancing.
*
* @group: sched_group belonging to the sched_domain under consideration.
* @sds: Variable containing the statistics of the sched_domain
* @local_group: Does group contain the CPU for which we're performing
* load balancing ?
* @sgs: Variable containing the statistics of the group.
*/
static inline void update_sd_power_savings_stats(struct sched_group *group,
struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
{
if (!sds->power_savings_balance)
return;
/*
* If the local group is idle or completely loaded
* no need to do power savings balance at this domain
*/
if (local_group && (sds->this_nr_running >= sgs->group_capacity ||
!sds->this_nr_running))
sds->power_savings_balance = 0;
/*
* If a group is already running at full capacity or idle,
* don't include that group in power savings calculations
*/
if (!sds->power_savings_balance ||
sgs->sum_nr_running >= sgs->group_capacity ||
!sgs->sum_nr_running)
return;
/*
* Calculate the group which has the least non-idle load.
* This is the group from where we need to pick up the load
* for saving power
*/
if ((sgs->sum_nr_running < sds->min_nr_running) ||
(sgs->sum_nr_running == sds->min_nr_running &&
group_first_cpu(group) > group_first_cpu(sds->group_min))) {
sds->group_min = group;
sds->min_nr_running = sgs->sum_nr_running;
sds->min_load_per_task = sgs->sum_weighted_load /
sgs->sum_nr_running;
}
/*
* Calculate the group which is almost near its
* capacity but still has some space to pick up some load
* from other group and save more power
*/
if (sgs->sum_nr_running + 1 > sgs->group_capacity)
return;
if (sgs->sum_nr_running > sds->leader_nr_running ||
(sgs->sum_nr_running == sds->leader_nr_running &&
group_first_cpu(group) < group_first_cpu(sds->group_leader))) {
sds->group_leader = group;
sds->leader_nr_running = sgs->sum_nr_running;
}
}
/**
* check_power_save_busiest_group - see if there is potential for some power-savings balance
* @sds: Variable containing the statistics of the sched_domain
* under consideration.
* @this_cpu: Cpu at which we're currently performing load-balancing.
* @imbalance: Variable to store the imbalance.
*
* Description:
* Check if we have potential to perform some power-savings balance.
* If yes, set the busiest group to be the least loaded group in the
* sched_domain, so that it's CPUs can be put to idle.
*
* Returns 1 if there is potential to perform power-savings balance.
* Else returns 0.
*/
static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
int this_cpu, unsigned long *imbalance)
{
if (!sds->power_savings_balance)
return 0;
if (sds->this != sds->group_leader ||
sds->group_leader == sds->group_min)
return 0;
*imbalance = sds->min_load_per_task;
sds->busiest = sds->group_min;
return 1;
}
#else /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
static inline void init_sd_power_savings_stats(struct sched_domain *sd,
struct sd_lb_stats *sds, enum cpu_idle_type idle)
{
return;
}
static inline void update_sd_power_savings_stats(struct sched_group *group,
struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs)
{
return;
}
static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
int this_cpu, unsigned long *imbalance)
{
return 0;
}
#endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */
static void rq_online_fair(struct rq *rq)
unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
{
update_sysctl();
return SCHED_LOAD_SCALE;
}
static void rq_offline_fair(struct rq *rq)
unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu)
{
return default_scale_freq_power(sd, cpu);
}
unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu)
{
unsigned long weight = cpumask_weight(sched_domain_span(sd));
unsigned long smt_gain = sd->smt_gain;
smt_gain /= weight;
return smt_gain;
}
unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
{
return default_scale_smt_power(sd, cpu);
}
unsigned long scale_rt_power(int cpu)
{
struct rq *rq = cpu_rq(cpu);
u64 total, available;
sched_avg_update(rq);
total = sched_avg_period() + (rq->clock - rq->age_stamp);
available = total - rq->rt_avg;
if (unlikely((s64)total < SCHED_LOAD_SCALE))
total = SCHED_LOAD_SCALE;
total >>= SCHED_LOAD_SHIFT;
return div_u64(available, total);
}
static void update_cpu_power(struct sched_domain *sd, int cpu)
{
unsigned long weight = cpumask_weight(sched_domain_span(sd));
unsigned long power = SCHED_LOAD_SCALE;
struct sched_group *sdg = sd->groups;
if (sched_feat(ARCH_POWER))
power *= arch_scale_freq_power(sd, cpu);
else
power *= default_scale_freq_power(sd, cpu);
power >>= SCHED_LOAD_SHIFT;
if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
if (sched_feat(ARCH_POWER))
power *= arch_scale_smt_power(sd, cpu);
else
power *= default_scale_smt_power(sd, cpu);
power >>= SCHED_LOAD_SHIFT;
}
power *= scale_rt_power(cpu);
power >>= SCHED_LOAD_SHIFT;
if (!power)
power = 1;
sdg->cpu_power = power;
}
static void update_group_power(struct sched_domain *sd, int cpu)
{
struct sched_domain *child = sd->child;
struct sched_group *group, *sdg = sd->groups;
unsigned long power;
if (!child) {
update_cpu_power(sd, cpu);
return;
}
power = 0;
group = child->groups;
do {
power += group->cpu_power;
group = group->next;
} while (group != child->groups);
sdg->cpu_power = power;
}
/**
* update_sg_lb_stats - Update sched_group's statistics for load balancing.
* @sd: The sched_domain whose statistics are to be updated.
* @group: sched_group whose statistics are to be updated.
* @this_cpu: Cpu for which load balance is currently performed.
* @idle: Idle status of this_cpu
* @load_idx: Load index of sched_domain of this_cpu for load calc.
* @sd_idle: Idle status of the sched_domain containing group.
* @local_group: Does group contain this_cpu.
* @cpus: Set of cpus considered for load balancing.
* @balance: Should we balance.
* @sgs: variable to hold the statistics for this group.
*/
static inline void update_sg_lb_stats(struct sched_domain *sd,
struct sched_group *group, int this_cpu,
enum cpu_idle_type idle, int load_idx, int *sd_idle,
int local_group, const struct cpumask *cpus,
int *balance, struct sg_lb_stats *sgs)
{
unsigned long load, max_cpu_load, min_cpu_load;
int i;
unsigned int balance_cpu = -1, first_idle_cpu = 0;
unsigned long avg_load_per_task = 0;
if (local_group)
balance_cpu = group_first_cpu(group);
/* Tally up the load of all CPUs in the group */
max_cpu_load = 0;
min_cpu_load = ~0UL;
for_each_cpu_and(i, sched_group_cpus(group), cpus) {
struct rq *rq = cpu_rq(i);
if (*sd_idle && rq->nr_running)
*sd_idle = 0;
/* Bias balancing toward cpus of our domain */
if (local_group) {
if (idle_cpu(i) && !first_idle_cpu) {
first_idle_cpu = 1;
balance_cpu = i;
}
load = target_load(i, load_idx);
} else {
load = source_load(i, load_idx);
if (load > max_cpu_load)
max_cpu_load = load;
if (min_cpu_load > load)
min_cpu_load = load;
}
sgs->group_load += load;
sgs->sum_nr_running += rq->nr_running;
sgs->sum_weighted_load += weighted_cpuload(i);
}
/*
* First idle cpu or the first cpu(busiest) in this sched group
* is eligible for doing load balancing at this and above
* domains. In the newly idle case, we will allow all the cpu's
* to do the newly idle load balance.
*/
if (idle != CPU_NEWLY_IDLE && local_group &&
balance_cpu != this_cpu) {
*balance = 0;
return;
}
update_group_power(sd, this_cpu);
/* Adjust by relative CPU power of the group */
sgs->avg_load = (sgs->group_load * SCHED_LOAD_SCALE) / group->cpu_power;
/*
* Consider the group unbalanced when the imbalance is larger
* than the average weight of two tasks.
*
* APZ: with cgroup the avg task weight can vary wildly and
* might not be a suitable number - should we keep a
* normalized nr_running number somewhere that negates
* the hierarchy?
*/
if (sgs->sum_nr_running)
avg_load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;
if ((max_cpu_load - min_cpu_load) > 2*avg_load_per_task)
sgs->group_imb = 1;
sgs->group_capacity =
DIV_ROUND_CLOSEST(group->cpu_power, SCHED_LOAD_SCALE);
}
/**
* update_sd_lb_stats - Update sched_group's statistics for load balancing.
* @sd: sched_domain whose statistics are to be updated.
* @this_cpu: Cpu for which load balance is currently performed.
* @idle: Idle status of this_cpu
* @sd_idle: Idle status of the sched_domain containing group.
* @cpus: Set of cpus considered for load balancing.
* @balance: Should we balance.
* @sds: variable to hold the statistics for this sched_domain.
*/
static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu,
enum cpu_idle_type idle, int *sd_idle,
const struct cpumask *cpus, int *balance,
struct sd_lb_stats *sds)
{
struct sched_domain *child = sd->child;
struct sched_group *group = sd->groups;
struct sg_lb_stats sgs;
int load_idx, prefer_sibling = 0;
if (child && child->flags & SD_PREFER_SIBLING)
prefer_sibling = 1;
init_sd_power_savings_stats(sd, sds, idle);
load_idx = get_sd_load_idx(sd, idle);
do {
int local_group;
local_group = cpumask_test_cpu(this_cpu,
sched_group_cpus(group));
memset(&sgs, 0, sizeof(sgs));
update_sg_lb_stats(sd, group, this_cpu, idle, load_idx, sd_idle,
local_group, cpus, balance, &sgs);
if (local_group && !(*balance))
return;
sds->total_load += sgs.group_load;
sds->total_pwr += group->cpu_power;
/*
* In case the child domain prefers tasks go to siblings
* first, lower the group capacity to one so that we'll try
* and move all the excess tasks away.
*/
if (prefer_sibling)
sgs.group_capacity = min(sgs.group_capacity, 1UL);
if (local_group) {
sds->this_load = sgs.avg_load;
sds->this = group;
sds->this_nr_running = sgs.sum_nr_running;
sds->this_load_per_task = sgs.sum_weighted_load;
} else if (sgs.avg_load > sds->max_load &&
(sgs.sum_nr_running > sgs.group_capacity ||
sgs.group_imb)) {
sds->max_load = sgs.avg_load;
sds->busiest = group;
sds->busiest_nr_running = sgs.sum_nr_running;
sds->busiest_group_capacity = sgs.group_capacity;
sds->busiest_load_per_task = sgs.sum_weighted_load;
sds->group_imb = sgs.group_imb;
}
update_sd_power_savings_stats(group, sds, local_group, &sgs);
group = group->next;
} while (group != sd->groups);
}
/**
* fix_small_imbalance - Calculate the minor imbalance that exists
* amongst the groups of a sched_domain, during
* load balancing.
* @sds: Statistics of the sched_domain whose imbalance is to be calculated.
* @this_cpu: The cpu at whose sched_domain we're performing load-balance.
* @imbalance: Variable to store the imbalance.
*/
static inline void fix_small_imbalance(struct sd_lb_stats *sds,
int this_cpu, unsigned long *imbalance)
{
unsigned long tmp, pwr_now = 0, pwr_move = 0;
unsigned int imbn = 2;
unsigned long scaled_busy_load_per_task;
if (sds->this_nr_running) {
sds->this_load_per_task /= sds->this_nr_running;
if (sds->busiest_load_per_task >
sds->this_load_per_task)
imbn = 1;
} else
sds->this_load_per_task =
cpu_avg_load_per_task(this_cpu);
scaled_busy_load_per_task = sds->busiest_load_per_task
* SCHED_LOAD_SCALE;
scaled_busy_load_per_task /= sds->busiest->cpu_power;
if (sds->max_load - sds->this_load + scaled_busy_load_per_task >=
(scaled_busy_load_per_task * imbn)) {
*imbalance = sds->busiest_load_per_task;
return;
}
/*
* OK, we don't have enough imbalance to justify moving tasks,
* however we may be able to increase total CPU power used by
* moving them.
*/
pwr_now += sds->busiest->cpu_power *
min(sds->busiest_load_per_task, sds->max_load);
pwr_now += sds->this->cpu_power *
min(sds->this_load_per_task, sds->this_load);
pwr_now /= SCHED_LOAD_SCALE;
/* Amount of load we'd subtract */
tmp = (sds->busiest_load_per_task * SCHED_LOAD_SCALE) /
sds->busiest->cpu_power;
if (sds->max_load > tmp)
pwr_move += sds->busiest->cpu_power *
min(sds->busiest_load_per_task, sds->max_load - tmp);
/* Amount of load we'd add */
if (sds->max_load * sds->busiest->cpu_power <
sds->busiest_load_per_task * SCHED_LOAD_SCALE)
tmp = (sds->max_load * sds->busiest->cpu_power) /
sds->this->cpu_power;
else
tmp = (sds->busiest_load_per_task * SCHED_LOAD_SCALE) /
sds->this->cpu_power;
pwr_move += sds->this->cpu_power *
min(sds->this_load_per_task, sds->this_load + tmp);
pwr_move /= SCHED_LOAD_SCALE;
/* Move if we gain throughput */
if (pwr_move > pwr_now)
*imbalance = sds->busiest_load_per_task;
}
/**
* calculate_imbalance - Calculate the amount of imbalance present within the
* groups of a given sched_domain during load balance.
* @sds: statistics of the sched_domain whose imbalance is to be calculated.
* @this_cpu: Cpu for which currently load balance is being performed.
* @imbalance: The variable to store the imbalance.
*/
static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu,
unsigned long *imbalance)
{
unsigned long max_pull, load_above_capacity = ~0UL;
sds->busiest_load_per_task /= sds->busiest_nr_running;
if (sds->group_imb) {
sds->busiest_load_per_task =
min(sds->busiest_load_per_task, sds->avg_load);
}
/*
* In the presence of smp nice balancing, certain scenarios can have
* max load less than avg load(as we skip the groups at or below
* its cpu_power, while calculating max_load..)
*/
if (sds->max_load < sds->avg_load) {
*imbalance = 0;
return fix_small_imbalance(sds, this_cpu, imbalance);
}
if (!sds->group_imb) {
/*
* Don't want to pull so many tasks that a group would go idle.
*/
load_above_capacity = (sds->busiest_nr_running -
sds->busiest_group_capacity);
load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_LOAD_SCALE);
load_above_capacity /= sds->busiest->cpu_power;
}
/*
* We're trying to get all the cpus to the average_load, so we don't
* want to push ourselves above the average load, nor do we wish to
* reduce the max loaded cpu below the average load. At the same time,
* we also don't want to reduce the group load below the group capacity
* (so that we can implement power-savings policies etc). Thus we look
* for the minimum possible imbalance.
* Be careful of negative numbers as they'll appear as very large values
* with unsigned longs.
*/
max_pull = min(sds->max_load - sds->avg_load, load_above_capacity);
/* How much load to actually move to equalise the imbalance */
*imbalance = min(max_pull * sds->busiest->cpu_power,
(sds->avg_load - sds->this_load) * sds->this->cpu_power)
/ SCHED_LOAD_SCALE;
/*
* if *imbalance is less than the average load per runnable task
* there is no gaurantee that any tasks will be moved so we'll have
* a think about bumping its value to force at least one task to be
* moved
*/
if (*imbalance < sds->busiest_load_per_task)
return fix_small_imbalance(sds, this_cpu, imbalance);
}
/******* find_busiest_group() helpers end here *********************/
/**
* find_busiest_group - Returns the busiest group within the sched_domain
* if there is an imbalance. If there isn't an imbalance, and
* the user has opted for power-savings, it returns a group whose
* CPUs can be put to idle by rebalancing those tasks elsewhere, if
* such a group exists.
*
* Also calculates the amount of weighted load which should be moved
* to restore balance.
*
* @sd: The sched_domain whose busiest group is to be returned.
* @this_cpu: The cpu for which load balancing is currently being performed.
* @imbalance: Variable which stores amount of weighted load which should
* be moved to restore balance/put a group to idle.
* @idle: The idle status of this_cpu.
* @sd_idle: The idleness of sd
* @cpus: The set of CPUs under consideration for load-balancing.
* @balance: Pointer to a variable indicating if this_cpu
* is the appropriate cpu to perform load balancing at this_level.
*
* Returns: - the busiest group if imbalance exists.
* - If no imbalance and user has opted for power-savings balance,
* return the least loaded group whose CPUs can be
* put to idle by rebalancing its tasks onto our group.
*/
static struct sched_group *
find_busiest_group(struct sched_domain *sd, int this_cpu,
unsigned long *imbalance, enum cpu_idle_type idle,
int *sd_idle, const struct cpumask *cpus, int *balance)
{
struct sd_lb_stats sds;
memset(&sds, 0, sizeof(sds));
/*
* Compute the various statistics relavent for load balancing at
* this level.
*/
update_sd_lb_stats(sd, this_cpu, idle, sd_idle, cpus,
balance, &sds);
/* Cases where imbalance does not exist from POV of this_cpu */
/* 1) this_cpu is not the appropriate cpu to perform load balancing
* at this level.
* 2) There is no busy sibling group to pull from.
* 3) This group is the busiest group.
* 4) This group is more busy than the avg busieness at this
* sched_domain.
* 5) The imbalance is within the specified limit.
*/
if (!(*balance))
goto ret;
if (!sds.busiest || sds.busiest_nr_running == 0)
goto out_balanced;
if (sds.this_load >= sds.max_load)
goto out_balanced;
sds.avg_load = (SCHED_LOAD_SCALE * sds.total_load) / sds.total_pwr;
if (sds.this_load >= sds.avg_load)
goto out_balanced;
if (100 * sds.max_load <= sd->imbalance_pct * sds.this_load)
goto out_balanced;
/* Looks like there is an imbalance. Compute it */
calculate_imbalance(&sds, this_cpu, imbalance);
return sds.busiest;
out_balanced:
/*
* There is no obvious imbalance. But check if we can do some balancing
* to save power.
*/
if (check_power_save_busiest_group(&sds, this_cpu, imbalance))
return sds.busiest;
ret:
*imbalance = 0;
return NULL;
}
/*
* find_busiest_queue - find the busiest runqueue among the cpus in group.
*/
static struct rq *
find_busiest_queue(struct sched_group *group, enum cpu_idle_type idle,
unsigned long imbalance, const struct cpumask *cpus)
{
struct rq *busiest = NULL, *rq;
unsigned long max_load = 0;
int i;
for_each_cpu(i, sched_group_cpus(group)) {
unsigned long power = power_of(i);
unsigned long capacity = DIV_ROUND_CLOSEST(power, SCHED_LOAD_SCALE);
unsigned long wl;
if (!cpumask_test_cpu(i, cpus))
continue;
rq = cpu_rq(i);
wl = weighted_cpuload(i);
/*
* When comparing with imbalance, use weighted_cpuload()
* which is not scaled with the cpu power.
*/
if (capacity && rq->nr_running == 1 && wl > imbalance)
continue;
/*
* For the load comparisons with the other cpu's, consider
* the weighted_cpuload() scaled with the cpu power, so that
* the load can be moved away from the cpu that is potentially
* running at a lower capacity.
*/
wl = (wl * SCHED_LOAD_SCALE) / power;
if (wl > max_load) {
max_load = wl;
busiest = rq;
}
}
return busiest;
}
/*
* Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
* so long as it is large enough.
*/
#define MAX_PINNED_INTERVAL 512
/* Working cpumask for load_balance and load_balance_newidle. */
static DEFINE_PER_CPU(cpumask_var_t, load_balance_tmpmask);
static int need_active_balance(struct sched_domain *sd, int sd_idle, int idle)
{
if (idle == CPU_NEWLY_IDLE) {
/*
* The only task running in a non-idle cpu can be moved to this
* cpu in an attempt to completely freeup the other CPU
* package.
*
* The package power saving logic comes from
* find_busiest_group(). If there are no imbalance, then
* f_b_g() will return NULL. However when sched_mc={1,2} then
* f_b_g() will select a group from which a running task may be
* pulled to this cpu in order to make the other package idle.
* If there is no opportunity to make a package idle and if
* there are no imbalance, then f_b_g() will return NULL and no
* action will be taken in load_balance_newidle().
*
* Under normal task pull operation due to imbalance, there
* will be more than one task in the source run queue and
* move_tasks() will succeed. ld_moved will be true and this
* active balance code will not be triggered.
*/
if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
return 0;
if (sched_mc_power_savings < POWERSAVINGS_BALANCE_WAKEUP)
return 0;
}
return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2);
}
/*
* Check this_cpu to ensure it is balanced within domain. Attempt to move
* tasks if there is an imbalance.
*/
static int load_balance(int this_cpu, struct rq *this_rq,
struct sched_domain *sd, enum cpu_idle_type idle,
int *balance)
{
int ld_moved, all_pinned = 0, active_balance = 0, sd_idle = 0;
struct sched_group *group;
unsigned long imbalance;
struct rq *busiest;
unsigned long flags;
struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask);
cpumask_copy(cpus, cpu_active_mask);
/*
* When power savings policy is enabled for the parent domain, idle
* sibling can pick up load irrespective of busy siblings. In this case,
* let the state of idle sibling percolate up as CPU_IDLE, instead of
* portraying it as CPU_NOT_IDLE.
*/
if (idle != CPU_NOT_IDLE && sd->flags & SD_SHARE_CPUPOWER &&
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
sd_idle = 1;
schedstat_inc(sd, lb_count[idle]);
redo:
update_shares(sd);
group = find_busiest_group(sd, this_cpu, &imbalance, idle, &sd_idle,
cpus, balance);
if (*balance == 0)
goto out_balanced;
if (!group) {
schedstat_inc(sd, lb_nobusyg[idle]);
goto out_balanced;
}
busiest = find_busiest_queue(group, idle, imbalance, cpus);
if (!busiest) {
schedstat_inc(sd, lb_nobusyq[idle]);
goto out_balanced;
}
BUG_ON(busiest == this_rq);
schedstat_add(sd, lb_imbalance[idle], imbalance);
ld_moved = 0;
if (busiest->nr_running > 1) {
/*
* Attempt to move tasks. If find_busiest_group has found
* an imbalance but busiest->nr_running <= 1, the group is
* still unbalanced. ld_moved simply stays zero, so it is
* correctly treated as an imbalance.
*/
local_irq_save(flags);
double_rq_lock(this_rq, busiest);
ld_moved = move_tasks(this_rq, this_cpu, busiest,
imbalance, sd, idle, &all_pinned);
double_rq_unlock(this_rq, busiest);
local_irq_restore(flags);
/*
* some other cpu did the load balance for us.
*/
if (ld_moved && this_cpu != smp_processor_id())
resched_cpu(this_cpu);
/* All tasks on this runqueue were pinned by CPU affinity */
if (unlikely(all_pinned)) {
cpumask_clear_cpu(cpu_of(busiest), cpus);
if (!cpumask_empty(cpus))
goto redo;
goto out_balanced;
}
}
if (!ld_moved) {
schedstat_inc(sd, lb_failed[idle]);
sd->nr_balance_failed++;
if (need_active_balance(sd, sd_idle, idle)) {
raw_spin_lock_irqsave(&busiest->lock, flags);
/* don't kick the migration_thread, if the curr
* task on busiest cpu can't be moved to this_cpu
*/
if (!cpumask_test_cpu(this_cpu,
&busiest->curr->cpus_allowed)) {
raw_spin_unlock_irqrestore(&busiest->lock,
flags);
all_pinned = 1;
goto out_one_pinned;
}
if (!busiest->active_balance) {
busiest->active_balance = 1;
busiest->push_cpu = this_cpu;
active_balance = 1;
}
raw_spin_unlock_irqrestore(&busiest->lock, flags);
if (active_balance)
wake_up_process(busiest->migration_thread);
/*
* We've kicked active balancing, reset the failure
* counter.
*/
sd->nr_balance_failed = sd->cache_nice_tries+1;
}
} else
sd->nr_balance_failed = 0;
if (likely(!active_balance)) {
/* We were unbalanced, so reset the balancing interval */
sd->balance_interval = sd->min_interval;
} else {
/*
* If we've begun active balancing, start to back off. This
* case may not be covered by the all_pinned logic if there
* is only 1 task on the busy runqueue (because we don't call
* move_tasks).
*/
if (sd->balance_interval < sd->max_interval)
sd->balance_interval *= 2;
}
if (!ld_moved && !sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
ld_moved = -1;
goto out;
out_balanced:
schedstat_inc(sd, lb_balanced[idle]);
sd->nr_balance_failed = 0;
out_one_pinned:
/* tune up the balancing interval */
if ((all_pinned && sd->balance_interval < MAX_PINNED_INTERVAL) ||
(sd->balance_interval < sd->max_interval))
sd->balance_interval *= 2;
if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
ld_moved = -1;
else
ld_moved = 0;
out:
if (ld_moved)
update_shares(sd);
return ld_moved;
}
/*
* idle_balance is called by schedule() if this_cpu is about to become
* idle. Attempts to pull tasks from other CPUs.
*/
static void idle_balance(int this_cpu, struct rq *this_rq)
{
struct sched_domain *sd;
int pulled_task = 0;
unsigned long next_balance = jiffies + HZ;
this_rq->idle_stamp = this_rq->clock;
if (this_rq->avg_idle < sysctl_sched_migration_cost)
return;
/*
* Drop the rq->lock, but keep IRQ/preempt disabled.
*/
raw_spin_unlock(&this_rq->lock);
for_each_domain(this_cpu, sd) {
unsigned long interval;
int balance = 1;
if (!(sd->flags & SD_LOAD_BALANCE))
continue;
if (sd->flags & SD_BALANCE_NEWIDLE) {
/* If we've pulled tasks over stop searching: */
pulled_task = load_balance(this_cpu, this_rq,
sd, CPU_NEWLY_IDLE, &balance);
}
interval = msecs_to_jiffies(sd->balance_interval);
if (time_after(next_balance, sd->last_balance + interval))
next_balance = sd->last_balance + interval;
if (pulled_task) {
this_rq->idle_stamp = 0;
break;
}
}
raw_spin_lock(&this_rq->lock);
if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
/*
* We are going idle. next_balance may be set based on
* a busy processor. So reset next_balance.
*/
this_rq->next_balance = next_balance;
}
}
/*
* active_load_balance is run by migration threads. It pushes running tasks
* off the busiest CPU onto idle CPUs. It requires at least 1 task to be
* running on each physical CPU where possible, and avoids physical /
* logical imbalances.
*
* Called with busiest_rq locked.
*/
static void active_load_balance(struct rq *busiest_rq, int busiest_cpu)
{
int target_cpu = busiest_rq->push_cpu;
struct sched_domain *sd;
struct rq *target_rq;
/* Is there any task to move? */
if (busiest_rq->nr_running <= 1)
return;
target_rq = cpu_rq(target_cpu);
/*
* This condition is "impossible", if it occurs
* we need to fix it. Originally reported by
* Bjorn Helgaas on a 128-cpu setup.
*/
BUG_ON(busiest_rq == target_rq);
/* move a task from busiest_rq to target_rq */
double_lock_balance(busiest_rq, target_rq);
update_rq_clock(busiest_rq);
update_rq_clock(target_rq);
/* Search for an sd spanning us and the target CPU. */
for_each_domain(target_cpu, sd) {
if ((sd->flags & SD_LOAD_BALANCE) &&
cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
break;
}
if (likely(sd)) {
schedstat_inc(sd, alb_count);
if (move_one_task(target_rq, target_cpu, busiest_rq,
sd, CPU_IDLE))
schedstat_inc(sd, alb_pushed);
else
schedstat_inc(sd, alb_failed);
}
double_unlock_balance(busiest_rq, target_rq);
}
#ifdef CONFIG_NO_HZ
static struct {
atomic_t load_balancer;
cpumask_var_t cpu_mask;
cpumask_var_t ilb_grp_nohz_mask;
} nohz ____cacheline_aligned = {
.load_balancer = ATOMIC_INIT(-1),
};
int get_nohz_load_balancer(void)
{
return atomic_read(&nohz.load_balancer);
}
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
/**
* lowest_flag_domain - Return lowest sched_domain containing flag.
* @cpu: The cpu whose lowest level of sched domain is to
* be returned.
* @flag: The flag to check for the lowest sched_domain
* for the given cpu.
*
* Returns the lowest sched_domain of a cpu which contains the given flag.
*/
static inline struct sched_domain *lowest_flag_domain(int cpu, int flag)
{
struct sched_domain *sd;
for_each_domain(cpu, sd)
if (sd && (sd->flags & flag))
break;
return sd;
}
/**
* for_each_flag_domain - Iterates over sched_domains containing the flag.
* @cpu: The cpu whose domains we're iterating over.
* @sd: variable holding the value of the power_savings_sd
* for cpu.
* @flag: The flag to filter the sched_domains to be iterated.
*
* Iterates over all the scheduler domains for a given cpu that has the 'flag'
* set, starting from the lowest sched_domain to the highest.
*/
#define for_each_flag_domain(cpu, sd, flag) \
for (sd = lowest_flag_domain(cpu, flag); \
(sd && (sd->flags & flag)); sd = sd->parent)
/**
* is_semi_idle_group - Checks if the given sched_group is semi-idle.
* @ilb_group: group to be checked for semi-idleness
*
* Returns: 1 if the group is semi-idle. 0 otherwise.
*
* We define a sched_group to be semi idle if it has atleast one idle-CPU
* and atleast one non-idle CPU. This helper function checks if the given
* sched_group is semi-idle or not.
*/
static inline int is_semi_idle_group(struct sched_group *ilb_group)
{
cpumask_and(nohz.ilb_grp_nohz_mask, nohz.cpu_mask,
sched_group_cpus(ilb_group));
/*
* A sched_group is semi-idle when it has atleast one busy cpu
* and atleast one idle cpu.
*/
if (cpumask_empty(nohz.ilb_grp_nohz_mask))
return 0;
if (cpumask_equal(nohz.ilb_grp_nohz_mask, sched_group_cpus(ilb_group)))
return 0;
return 1;
}
/**
* find_new_ilb - Finds the optimum idle load balancer for nomination.
* @cpu: The cpu which is nominating a new idle_load_balancer.
*
* Returns: Returns the id of the idle load balancer if it exists,
* Else, returns >= nr_cpu_ids.
*
* This algorithm picks the idle load balancer such that it belongs to a
* semi-idle powersavings sched_domain. The idea is to try and avoid
* completely idle packages/cores just for the purpose of idle load balancing
* when there are other idle cpu's which are better suited for that job.
*/
static int find_new_ilb(int cpu)
{
struct sched_domain *sd;
struct sched_group *ilb_group;
/*
* Have idle load balancer selection from semi-idle packages only
* when power-aware load balancing is enabled
*/
if (!(sched_smt_power_savings || sched_mc_power_savings))
goto out_done;
/*
* Optimize for the case when we have no idle CPUs or only one
* idle CPU. Don't walk the sched_domain hierarchy in such cases
*/
if (cpumask_weight(nohz.cpu_mask) < 2)
goto out_done;
for_each_flag_domain(cpu, sd, SD_POWERSAVINGS_BALANCE) {
ilb_group = sd->groups;
do {
if (is_semi_idle_group(ilb_group))
return cpumask_first(nohz.ilb_grp_nohz_mask);
ilb_group = ilb_group->next;
} while (ilb_group != sd->groups);
}
out_done:
return cpumask_first(nohz.cpu_mask);
}
#else /* (CONFIG_SCHED_MC || CONFIG_SCHED_SMT) */
static inline int find_new_ilb(int call_cpu)
{
return cpumask_first(nohz.cpu_mask);
}
#endif
/*
* This routine will try to nominate the ilb (idle load balancing)
* owner among the cpus whose ticks are stopped. ilb owner will do the idle
* load balancing on behalf of all those cpus. If all the cpus in the system
* go into this tickless mode, then there will be no ilb owner (as there is
* no need for one) and all the cpus will sleep till the next wakeup event
* arrives...
*
* For the ilb owner, tick is not stopped. And this tick will be used
* for idle load balancing. ilb owner will still be part of
* nohz.cpu_mask..
*
* While stopping the tick, this cpu will become the ilb owner if there
* is no other owner. And will be the owner till that cpu becomes busy
* or if all cpus in the system stop their ticks at which point
* there is no need for ilb owner.
*
* When the ilb owner becomes busy, it nominates another owner, during the
* next busy scheduler_tick()
*/
int select_nohz_load_balancer(int stop_tick)
{
int cpu = smp_processor_id();
if (stop_tick) {
cpu_rq(cpu)->in_nohz_recently = 1;
if (!cpu_active(cpu)) {
if (atomic_read(&nohz.load_balancer) != cpu)
return 0;
/*
* If we are going offline and still the leader,
* give up!
*/
if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
BUG();
return 0;
}
cpumask_set_cpu(cpu, nohz.cpu_mask);
/* time for ilb owner also to sleep */
if (cpumask_weight(nohz.cpu_mask) == num_active_cpus()) {
if (atomic_read(&nohz.load_balancer) == cpu)
atomic_set(&nohz.load_balancer, -1);
return 0;
}
if (atomic_read(&nohz.load_balancer) == -1) {
/* make me the ilb owner */
if (atomic_cmpxchg(&nohz.load_balancer, -1, cpu) == -1)
return 1;
} else if (atomic_read(&nohz.load_balancer) == cpu) {
int new_ilb;
if (!(sched_smt_power_savings ||
sched_mc_power_savings))
return 1;
/*
* Check to see if there is a more power-efficient
* ilb.
*/
new_ilb = find_new_ilb(cpu);
if (new_ilb < nr_cpu_ids && new_ilb != cpu) {
atomic_set(&nohz.load_balancer, -1);
resched_cpu(new_ilb);
return 0;
}
return 1;
}
} else {
if (!cpumask_test_cpu(cpu, nohz.cpu_mask))
return 0;
cpumask_clear_cpu(cpu, nohz.cpu_mask);
if (atomic_read(&nohz.load_balancer) == cpu)
if (atomic_cmpxchg(&nohz.load_balancer, cpu, -1) != cpu)
BUG();
}
return 0;
}
#endif
static DEFINE_SPINLOCK(balancing);
/*
* It checks each scheduling domain to see if it is due to be balanced,
* and initiates a balancing operation if so.
*
* Balancing parameters are set up in arch_init_sched_domains.
*/
static void rebalance_domains(int cpu, enum cpu_idle_type idle)
{
int balance = 1;
struct rq *rq = cpu_rq(cpu);
unsigned long interval;
struct sched_domain *sd;
/* Earliest time when we have to do rebalance again */
unsigned long next_balance = jiffies + 60*HZ;
int update_next_balance = 0;
int need_serialize;
for_each_domain(cpu, sd) {
if (!(sd->flags & SD_LOAD_BALANCE))
continue;
interval = sd->balance_interval;
if (idle != CPU_IDLE)
interval *= sd->busy_factor;
/* scale ms to jiffies */
interval = msecs_to_jiffies(interval);
if (unlikely(!interval))
interval = 1;
if (interval > HZ*NR_CPUS/10)
interval = HZ*NR_CPUS/10;
need_serialize = sd->flags & SD_SERIALIZE;
if (need_serialize) {
if (!spin_trylock(&balancing))
goto out;
}
if (time_after_eq(jiffies, sd->last_balance + interval)) {
if (load_balance(cpu, rq, sd, idle, &balance)) {
/*
* We've pulled tasks over so either we're no
* longer idle, or one of our SMT siblings is
* not idle.
*/
idle = CPU_NOT_IDLE;
}
sd->last_balance = jiffies;
}
if (need_serialize)
spin_unlock(&balancing);
out:
if (time_after(next_balance, sd->last_balance + interval)) {
next_balance = sd->last_balance + interval;
update_next_balance = 1;
}
/*
* Stop the load balance at this level. There is another
* CPU in our sched group which is doing load balancing more
* actively.
*/
if (!balance)
break;
}
/*
* next_balance will be updated only when there is a need.
* When the cpu is attached to null domain for ex, it will not be
* updated.
*/
if (likely(update_next_balance))
rq->next_balance = next_balance;
}
/*
* run_rebalance_domains is triggered when needed from the scheduler tick.
* In CONFIG_NO_HZ case, the idle load balance owner will do the
* rebalancing for all the cpus for whom scheduler ticks are stopped.
*/
static void run_rebalance_domains(struct softirq_action *h)
{
int this_cpu = smp_processor_id();
struct rq *this_rq = cpu_rq(this_cpu);
enum cpu_idle_type idle = this_rq->idle_at_tick ?
CPU_IDLE : CPU_NOT_IDLE;
rebalance_domains(this_cpu, idle);
#ifdef CONFIG_NO_HZ
/*
* If this cpu is the owner for idle load balancing, then do the
* balancing on behalf of the other idle cpus whose ticks are
* stopped.
*/
if (this_rq->idle_at_tick &&
atomic_read(&nohz.load_balancer) == this_cpu) {
struct rq *rq;
int balance_cpu;
for_each_cpu(balance_cpu, nohz.cpu_mask) {
if (balance_cpu == this_cpu)
continue;
/*
* If this cpu gets work to do, stop the load balancing
* work being done for other cpus. Next load
* balancing owner will pick it up.
*/
if (need_resched())
break;
rebalance_domains(balance_cpu, CPU_IDLE);
rq = cpu_rq(balance_cpu);
if (time_after(this_rq->next_balance, rq->next_balance))
this_rq->next_balance = rq->next_balance;
}
}
#endif
}
static inline int on_null_domain(int cpu)
{
return !rcu_dereference(cpu_rq(cpu)->sd);
}
/*
* Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
*
* In case of CONFIG_NO_HZ, this is the place where we nominate a new
* idle load balancing owner or decide to stop the periodic load balancing,
* if the whole system is idle.
*/
static inline void trigger_load_balance(struct rq *rq, int cpu)
{
#ifdef CONFIG_NO_HZ
/*
* If we were in the nohz mode recently and busy at the current
* scheduler tick, then check if we need to nominate new idle
* load balancer.
*/
if (rq->in_nohz_recently && !rq->idle_at_tick) {
rq->in_nohz_recently = 0;
if (atomic_read(&nohz.load_balancer) == cpu) {
cpumask_clear_cpu(cpu, nohz.cpu_mask);
atomic_set(&nohz.load_balancer, -1);
}
if (atomic_read(&nohz.load_balancer) == -1) {
int ilb = find_new_ilb(cpu);
if (ilb < nr_cpu_ids)
resched_cpu(ilb);
}
}
/*
* If this cpu is idle and doing idle load balancing for all the
* cpus with ticks stopped, is it time for that to stop?
*/
if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) == cpu &&
cpumask_weight(nohz.cpu_mask) == num_online_cpus()) {
resched_cpu(cpu);
return;
}
/*
* If this cpu is idle and the idle load balancing is done by
* someone else, then no need raise the SCHED_SOFTIRQ
*/
if (rq->idle_at_tick && atomic_read(&nohz.load_balancer) != cpu &&
cpumask_test_cpu(cpu, nohz.cpu_mask))
return;
#endif
/* Don't need to rebalance while attached to NULL domain */
if (time_after_eq(jiffies, rq->next_balance) &&
likely(!on_null_domain(cpu)))
raise_softirq(SCHED_SOFTIRQ);
}
static void rq_online_fair(struct rq *rq)
{
update_sysctl();
}
static void rq_offline_fair(struct rq *rq)
{
update_sysctl();
}
#else /* CONFIG_SMP */
/*
* on UP we do not need to balance between CPUs:
*/
static inline void idle_balance(int cpu, struct rq *rq)
{
update_sysctl();
}
#endif /* CONFIG_SMP */
......@@ -2076,7 +3667,7 @@ static void moved_group_fair(struct task_struct *p, int on_rq)
}
#endif
unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
{
struct sched_entity *se = &task->se;
unsigned int rr_interval = 0;
......@@ -2108,8 +3699,6 @@ static const struct sched_class fair_sched_class = {
#ifdef CONFIG_SMP
.select_task_rq = select_task_rq_fair,
.load_balance = load_balance_fair,
.move_one_task = move_one_task_fair,
.rq_online = rq_online_fair,
.rq_offline = rq_offline_fair,
......
kernel/sched_idletask.c
View file @ f66ffded
......@@ -44,24 +44,6 @@ static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
{
}
#ifdef CONFIG_SMP
static unsigned long
load_balance_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
unsigned long max_load_move,
struct sched_domain *sd, enum cpu_idle_type idle,
int *all_pinned, int *this_best_prio)
{
return 0;
}
static int
move_one_task_idle(struct rq *this_rq, int this_cpu, struct rq *busiest,
struct sched_domain *sd, enum cpu_idle_type idle)
{
return 0;
}
#endif
static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued)
{
}
......@@ -97,7 +79,7 @@ static void prio_changed_idle(struct rq *rq, struct task_struct *p,
check_preempt_curr(rq, p, 0);
}
unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task)
static unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task)
{
return 0;
}
......@@ -119,9 +101,6 @@ static const struct sched_class idle_sched_class = {
#ifdef CONFIG_SMP
.select_task_rq = select_task_rq_idle,
.load_balance = load_balance_idle,
.move_one_task = move_one_task_idle,
#endif
.set_curr_task = set_curr_task_idle,
......
kernel/sched_rt.c
View file @ f66ffded
......@@ -194,17 +194,20 @@ static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
return rt_se->my_q;
}
static void enqueue_rt_entity(struct sched_rt_entity *rt_se);
static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head);
static void dequeue_rt_entity(struct sched_rt_entity *rt_se);
static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
{
int this_cpu = smp_processor_id();
struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
struct sched_rt_entity *rt_se = rt_rq->rt_se;
struct sched_rt_entity *rt_se;
rt_se = rt_rq->tg->rt_se[this_cpu];
if (rt_rq->rt_nr_running) {
if (rt_se && !on_rt_rq(rt_se))
enqueue_rt_entity(rt_se);
enqueue_rt_entity(rt_se, false);
if (rt_rq->highest_prio.curr < curr->prio)
resched_task(curr);
}
......@@ -212,7 +215,10 @@ static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
{
struct sched_rt_entity *rt_se = rt_rq->rt_se;
int this_cpu = smp_processor_id();
struct sched_rt_entity *rt_se;
rt_se = rt_rq->tg->rt_se[this_cpu];
if (rt_se && on_rt_rq(rt_se))
dequeue_rt_entity(rt_se);
......@@ -803,7 +809,7 @@ void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
dec_rt_group(rt_se, rt_rq);
}
static void __enqueue_rt_entity(struct sched_rt_entity *rt_se)
static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
{
struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
struct rt_prio_array *array = &rt_rq->active;
......@@ -819,7 +825,10 @@ static void __enqueue_rt_entity(struct sched_rt_entity *rt_se)
if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running))
return;
list_add_tail(&rt_se->run_list, queue);
if (head)
list_add(&rt_se->run_list, queue);
else
list_add_tail(&rt_se->run_list, queue);
__set_bit(rt_se_prio(rt_se), array->bitmap);
inc_rt_tasks(rt_se, rt_rq);
......@@ -856,11 +865,11 @@ static void dequeue_rt_stack(struct sched_rt_entity *rt_se)
}
}
static void enqueue_rt_entity(struct sched_rt_entity *rt_se)
static void enqueue_rt_entity(struct sched_rt_entity *rt_se, bool head)
{
dequeue_rt_stack(rt_se);
for_each_sched_rt_entity(rt_se)
__enqueue_rt_entity(rt_se);
__enqueue_rt_entity(rt_se, head);
}
static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
......@@ -871,21 +880,22 @@ static void dequeue_rt_entity(struct sched_rt_entity *rt_se)
struct rt_rq *rt_rq = group_rt_rq(rt_se);
if (rt_rq && rt_rq->rt_nr_running)
__enqueue_rt_entity(rt_se);
__enqueue_rt_entity(rt_se, false);
}
}
/*
* Adding/removing a task to/from a priority array:
*/
static void enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup)
static void
enqueue_task_rt(struct rq *rq, struct task_struct *p, int wakeup, bool head)
{
struct sched_rt_entity *rt_se = &p->rt;
if (wakeup)
rt_se->timeout = 0;
enqueue_rt_entity(rt_se);
enqueue_rt_entity(rt_se, head);
if (!task_current(rq, p) && p->rt.nr_cpus_allowed > 1)
enqueue_pushable_task(rq, p);
......@@ -1481,24 +1491,6 @@ static void task_woken_rt(struct rq *rq, struct task_struct *p)
push_rt_tasks(rq);
}
static unsigned long
load_balance_rt(struct rq *this_rq, int this_cpu, struct rq *busiest,
unsigned long max_load_move,
struct sched_domain *sd, enum cpu_idle_type idle,
int *all_pinned, int *this_best_prio)
{
/* don't touch RT tasks */
return 0;
}
static int
move_one_task_rt(struct rq *this_rq, int this_cpu, struct rq *busiest,
struct sched_domain *sd, enum cpu_idle_type idle)
{
/* don't touch RT tasks */
return 0;
}
static void set_cpus_allowed_rt(struct task_struct *p,
const struct cpumask *new_mask)
{
......@@ -1721,7 +1713,7 @@ static void set_curr_task_rt(struct rq *rq)
dequeue_pushable_task(rq, p);
}
unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
{
/*
* Time slice is 0 for SCHED_FIFO tasks
......@@ -1746,8 +1738,6 @@ static const struct sched_class rt_sched_class = {
#ifdef CONFIG_SMP
.select_task_rq = select_task_rq_rt,
.load_balance = load_balance_rt,
.move_one_task = move_one_task_rt,
.set_cpus_allowed = set_cpus_allowed_rt,
.rq_online = rq_online_rt,
.rq_offline = rq_offline_rt,
......
kernel/sys.c
View file @ f66ffded
......@@ -571,11 +571,6 @@ static int set_user(struct cred *new)
if (!new_user)
return -EAGAIN;
if (!task_can_switch_user(new_user, current)) {
free_uid(new_user);
return -EINVAL;
}
if (atomic_read(&new_user->processes) >=
current->signal->rlim[RLIMIT_NPROC].rlim_cur &&
new_user != INIT_USER) {
......
kernel/user.c
View file @ f66ffded
......@@ -56,9 +56,6 @@ struct user_struct root_user = {
.sigpending = ATOMIC_INIT(0),
.locked_shm = 0,
.user_ns = &init_user_ns,
#ifdef CONFIG_USER_SCHED
.tg = &init_task_group,
#endif
};
/*
......@@ -75,268 +72,6 @@ static void uid_hash_remove(struct user_struct *up)
put_user_ns(up->user_ns);
}
#ifdef CONFIG_USER_SCHED
static void sched_destroy_user(struct user_struct *up)
{
sched_destroy_group(up->tg);
}
static int sched_create_user(struct user_struct *up)
{
int rc = 0;
up->tg = sched_create_group(&root_task_group);
if (IS_ERR(up->tg))
rc = -ENOMEM;
set_tg_uid(up);
return rc;
}
#else /* CONFIG_USER_SCHED */
static void sched_destroy_user(struct user_struct *up) { }
static int sched_create_user(struct user_struct *up) { return 0; }
#endif /* CONFIG_USER_SCHED */
#if defined(CONFIG_USER_SCHED) && defined(CONFIG_SYSFS)
static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
{
struct user_struct *user;
struct hlist_node *h;
hlist_for_each_entry(user, h, hashent, uidhash_node) {
if (user->uid == uid) {
/* possibly resurrect an "almost deleted" object */
if (atomic_inc_return(&user->__count) == 1)
cancel_delayed_work(&user->work);
return user;
}
}
return NULL;
}
static struct kset *uids_kset; /* represents the /sys/kernel/uids/ directory */
static DEFINE_MUTEX(uids_mutex);
static inline void uids_mutex_lock(void)
{
mutex_lock(&uids_mutex);
}
static inline void uids_mutex_unlock(void)
{
mutex_unlock(&uids_mutex);
}
/* uid directory attributes */
#ifdef CONFIG_FAIR_GROUP_SCHED
static ssize_t cpu_shares_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
struct user_struct *up = container_of(kobj, struct user_struct, kobj);
return sprintf(buf, "%lu\n", sched_group_shares(up->tg));
}
static ssize_t cpu_shares_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t size)
{
struct user_struct *up = container_of(kobj, struct user_struct, kobj);
unsigned long shares;
int rc;
sscanf(buf, "%lu", &shares);
rc = sched_group_set_shares(up->tg, shares);
return (rc ? rc : size);
}
static struct kobj_attribute cpu_share_attr =
__ATTR(cpu_share, 0644, cpu_shares_show, cpu_shares_store);
#endif
#ifdef CONFIG_RT_GROUP_SCHED
static ssize_t cpu_rt_runtime_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
struct user_struct *up = container_of(kobj, struct user_struct, kobj);
return sprintf(buf, "%ld\n", sched_group_rt_runtime(up->tg));
}
static ssize_t cpu_rt_runtime_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t size)
{
struct user_struct *up = container_of(kobj, struct user_struct, kobj);
unsigned long rt_runtime;
int rc;
sscanf(buf, "%ld", &rt_runtime);
rc = sched_group_set_rt_runtime(up->tg, rt_runtime);
return (rc ? rc : size);
}
static struct kobj_attribute cpu_rt_runtime_attr =
__ATTR(cpu_rt_runtime, 0644, cpu_rt_runtime_show, cpu_rt_runtime_store);
static ssize_t cpu_rt_period_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
struct user_struct *up = container_of(kobj, struct user_struct, kobj);
return sprintf(buf, "%lu\n", sched_group_rt_period(up->tg));
}
static ssize_t cpu_rt_period_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t size)
{
struct user_struct *up = container_of(kobj, struct user_struct, kobj);
unsigned long rt_period;
int rc;
sscanf(buf, "%lu", &rt_period);
rc = sched_group_set_rt_period(up->tg, rt_period);
return (rc ? rc : size);
}
static struct kobj_attribute cpu_rt_period_attr =
__ATTR(cpu_rt_period, 0644, cpu_rt_period_show, cpu_rt_period_store);
#endif
/* default attributes per uid directory */
static struct attribute *uids_attributes[] = {
#ifdef CONFIG_FAIR_GROUP_SCHED
&cpu_share_attr.attr,
#endif
#ifdef CONFIG_RT_GROUP_SCHED
&cpu_rt_runtime_attr.attr,
&cpu_rt_period_attr.attr,
#endif
NULL
};
/* the lifetime of user_struct is not managed by the core (now) */
static void uids_release(struct kobject *kobj)
{
return;
}
static struct kobj_type uids_ktype = {
.sysfs_ops = &kobj_sysfs_ops,
.default_attrs = uids_attributes,
.release = uids_release,
};
/*
* Create /sys/kernel/uids/<uid>/cpu_share file for this user
* We do not create this file for users in a user namespace (until
* sysfs tagging is implemented).
*
* See Documentation/scheduler/sched-design-CFS.txt for ramifications.
*/
static int uids_user_create(struct user_struct *up)
{
struct kobject *kobj = &up->kobj;
int error;
memset(kobj, 0, sizeof(struct kobject));
if (up->user_ns != &init_user_ns)
return 0;
kobj->kset = uids_kset;
error = kobject_init_and_add(kobj, &uids_ktype, NULL, "%d", up->uid);
if (error) {
kobject_put(kobj);
goto done;
}
kobject_uevent(kobj, KOBJ_ADD);
done:
return error;
}
/* create these entries in sysfs:
* "/sys/kernel/uids" directory
* "/sys/kernel/uids/0" directory (for root user)
* "/sys/kernel/uids/0/cpu_share" file (for root user)
*/
int __init uids_sysfs_init(void)
{
uids_kset = kset_create_and_add("uids", NULL, kernel_kobj);
if (!uids_kset)
return -ENOMEM;
return uids_user_create(&root_user);
}
/* delayed work function to remove sysfs directory for a user and free up
* corresponding structures.
*/
static void cleanup_user_struct(struct work_struct *w)
{
struct user_struct *up = container_of(w, struct user_struct, work.work);
unsigned long flags;
int remove_user = 0;
/* Make uid_hash_remove() + sysfs_remove_file() + kobject_del()
* atomic.
*/
uids_mutex_lock();
spin_lock_irqsave(&uidhash_lock, flags);
if (atomic_read(&up->__count) == 0) {
uid_hash_remove(up);
remove_user = 1;
}
spin_unlock_irqrestore(&uidhash_lock, flags);
if (!remove_user)
goto done;
if (up->user_ns == &init_user_ns) {
kobject_uevent(&up->kobj, KOBJ_REMOVE);
kobject_del(&up->kobj);
kobject_put(&up->kobj);
}
sched_destroy_user(up);
key_put(up->uid_keyring);
key_put(up->session_keyring);
kmem_cache_free(uid_cachep, up);
done:
uids_mutex_unlock();
}
/* IRQs are disabled and uidhash_lock is held upon function entry.
* IRQ state (as stored in flags) is restored and uidhash_lock released
* upon function exit.
*/
static void free_user(struct user_struct *up, unsigned long flags)
{
INIT_DELAYED_WORK(&up->work, cleanup_user_struct);
schedule_delayed_work(&up->work, msecs_to_jiffies(1000));
spin_unlock_irqrestore(&uidhash_lock, flags);
}
#else /* CONFIG_USER_SCHED && CONFIG_SYSFS */
static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
{
struct user_struct *user;
......@@ -352,11 +87,6 @@ static struct user_struct *uid_hash_find(uid_t uid, struct hlist_head *hashent)
return NULL;
}
int uids_sysfs_init(void) { return 0; }
static inline int uids_user_create(struct user_struct *up) { return 0; }
static inline void uids_mutex_lock(void) { }
static inline void uids_mutex_unlock(void) { }
/* IRQs are disabled and uidhash_lock is held upon function entry.
* IRQ state (as stored in flags) is restored and uidhash_lock released
* upon function exit.
......@@ -365,32 +95,11 @@ static void free_user(struct user_struct *up, unsigned long flags)
{
uid_hash_remove(up);
spin_unlock_irqrestore(&uidhash_lock, flags);
sched_destroy_user(up);
key_put(up->uid_keyring);
key_put(up->session_keyring);
kmem_cache_free(uid_cachep, up);
}
#endif
#if defined(CONFIG_RT_GROUP_SCHED) && defined(CONFIG_USER_SCHED)
/*
* We need to check if a setuid can take place. This function should be called
* before successfully completing the setuid.
*/
int task_can_switch_user(struct user_struct *up, struct task_struct *tsk)
{
return sched_rt_can_attach(up->tg, tsk);
}
#else
int task_can_switch_user(struct user_struct *up, struct task_struct *tsk)
{
return 1;
}
#endif
/*
* Locate the user_struct for the passed UID. If found, take a ref on it. The
* caller must undo that ref with free_uid().
......@@ -431,8 +140,6 @@ struct user_struct *alloc_uid(struct user_namespace *ns, uid_t uid)
/* Make uid_hash_find() + uids_user_create() + uid_hash_insert()
* atomic.
*/
uids_mutex_lock();
spin_lock_irq(&uidhash_lock);
up = uid_hash_find(uid, hashent);
spin_unlock_irq(&uidhash_lock);
......@@ -445,14 +152,8 @@ struct user_struct *alloc_uid(struct user_namespace *ns, uid_t uid)
new->uid = uid;
atomic_set(&new->__count, 1);
if (sched_create_user(new) < 0)
goto out_free_user;
new->user_ns = get_user_ns(ns);
if (uids_user_create(new))
goto out_destoy_sched;
/*
* Before adding this, check whether we raced
* on adding the same user already..
......@@ -475,17 +176,11 @@ struct user_struct *alloc_uid(struct user_namespace *ns, uid_t uid)
spin_unlock_irq(&uidhash_lock);
}
uids_mutex_unlock();
return up;
out_destoy_sched:
sched_destroy_user(new);
put_user_ns(new->user_ns);
out_free_user:
kmem_cache_free(uid_cachep, new);
out_unlock:
uids_mutex_unlock();
return NULL;
}
......
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