Commit 0ed4dd24 authored by Ingo Molnar's avatar Ingo Molnar

- rq-lock optimization in the preemption case, from Robert Love, plus some more cleanups.

parent 2b75b535
......@@ -157,6 +157,12 @@ do { \
preempt_enable(); \
} while (0)
#define spin_unlock_no_resched(lock) \
do { \
_raw_spin_unlock(lock); \
preempt_enable_no_resched(); \
} while (0)
#define read_lock(lock) ({preempt_disable(); _raw_read_lock(lock);})
#define read_unlock(lock) ({_raw_read_unlock(lock); preempt_enable();})
#define write_lock(lock) ({preempt_disable(); _raw_write_lock(lock);})
......@@ -174,6 +180,7 @@ do { \
#define spin_lock(lock) _raw_spin_lock(lock)
#define spin_trylock(lock) _raw_spin_trylock(lock)
#define spin_unlock(lock) _raw_spin_unlock(lock)
#define spin_unlock_no_resched(lock) _raw_spin_unlock(lock)
#define read_lock(lock) _raw_read_lock(lock)
#define read_unlock(lock) _raw_read_unlock(lock)
......
......@@ -152,17 +152,21 @@ static struct runqueue runqueues[NR_CPUS] __cacheline_aligned;
#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
#define rt_task(p) ((p)->prio < MAX_RT_PRIO)
/*
* task_rq_lock - lock the runqueue a given task resides on and disable
* interrupts. Note the ordering: we can safely lookup the task_rq without
* explicitly disabling preemption.
*/
static inline runqueue_t *task_rq_lock(task_t *p, unsigned long *flags)
{
struct runqueue *rq;
repeat_lock_task:
preempt_disable();
local_irq_save(*flags);
rq = task_rq(p);
spin_lock_irqsave(&rq->lock, *flags);
spin_lock(&rq->lock);
if (unlikely(rq != task_rq(p))) {
spin_unlock_irqrestore(&rq->lock, *flags);
preempt_enable();
goto repeat_lock_task;
}
return rq;
......@@ -171,7 +175,23 @@ static inline runqueue_t *task_rq_lock(task_t *p, unsigned long *flags)
static inline void task_rq_unlock(runqueue_t *rq, unsigned long *flags)
{
spin_unlock_irqrestore(&rq->lock, *flags);
preempt_enable();
}
/*
* rq_lock - lock a given runqueue and disable interrupts.
*/
static inline runqueue_t *rq_lock(runqueue_t *rq)
{
local_irq_disable();
rq = this_rq();
spin_lock(&rq->lock);
return rq;
}
static inline void rq_unlock(runqueue_t *rq)
{
spin_unlock(&rq->lock);
local_irq_enable();
}
/*
......@@ -364,9 +384,7 @@ void wake_up_forked_process(task_t * p)
{
runqueue_t *rq;
preempt_disable();
rq = this_rq();
spin_lock_irq(&rq->lock);
rq = rq_lock(rq);
p->state = TASK_RUNNING;
if (!rt_task(p)) {
......@@ -382,8 +400,7 @@ void wake_up_forked_process(task_t * p)
p->thread_info->cpu = smp_processor_id();
activate_task(p, rq);
spin_unlock_irq(&rq->lock);
preempt_enable();
rq_unlock(rq);
}
/*
......@@ -1367,8 +1384,7 @@ asmlinkage long sys_sched_yield(void)
runqueue_t *rq;
prio_array_t *array;
preempt_disable();
rq = this_rq();
rq = rq_lock(rq);
/*
* Decrease the yielding task's priority by one, to avoid
......@@ -1378,7 +1394,6 @@ asmlinkage long sys_sched_yield(void)
* If priority is already MAX_PRIO-1 then we still
* roundrobin the task within the runlist.
*/
spin_lock_irq(&rq->lock);
array = current->array;
/*
* If the task has reached maximum priority (or is a RT task)
......@@ -1395,8 +1410,7 @@ asmlinkage long sys_sched_yield(void)
list_add_tail(&current->run_list, array->queue + current->prio);
__set_bit(current->prio, array->bitmap);
}
spin_unlock(&rq->lock);
preempt_enable_no_resched();
spin_unlock_no_resched(&rq->lock);
schedule();
......
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