From a8a51d5e59561aa5b4d66e19eca819b537783e8f Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Fri, 27 Jun 2008 13:41:26 +0200
Subject: [PATCH] sched: persistent average load per task
Remove the fall-back to SCHED_LOAD_SCALE by remembering the previous value of
cpu_avg_load_per_task() - this is useful because of the hierarchical group
model in which task weight can be much smaller.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/sched.c | 25 ++++++++++++-------------
1 file changed, 12 insertions(+), 13 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c
index 39d5495540d2..6a6b0139eb32 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -554,6 +554,8 @@ struct rq {
int cpu;
int online;
+ unsigned long avg_load_per_task;
+
struct task_struct *migration_thread;
struct list_head migration_queue;
#endif
@@ -1427,9 +1429,18 @@ static inline void dec_cpu_load(struct rq *rq, unsigned long load)
#ifdef CONFIG_SMP
static unsigned long source_load(int cpu, int type);
static unsigned long target_load(int cpu, int type);
-static unsigned long cpu_avg_load_per_task(int cpu);
static int task_hot(struct task_struct *p, u64 now, struct sched_domain *sd);
+static unsigned long cpu_avg_load_per_task(int cpu)
+{
+ struct rq *rq = cpu_rq(cpu);
+
+ if (rq->nr_running)
+ rq->avg_load_per_task = rq->load.weight / rq->nr_running;
+
+ return rq->avg_load_per_task;
+}
+
#ifdef CONFIG_FAIR_GROUP_SCHED
typedef void (*tg_visitor)(struct task_group *, int, struct sched_domain *);
@@ -2010,18 +2021,6 @@ static unsigned long target_load(int cpu, int type)
return max(rq->cpu_load[type-1], total);
}
-/*
- * Return the average load per task on the cpu's run queue
- */
-static unsigned long cpu_avg_load_per_task(int cpu)
-{
- struct rq *rq = cpu_rq(cpu);
- unsigned long total = weighted_cpuload(cpu);
- unsigned long n = rq->nr_running;
-
- return n ? total / n : SCHED_LOAD_SCALE;
-}
-
/*
* find_idlest_group finds and returns the least busy CPU group within the
* domain.
--
2.30.9