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sched: small optimisation of can_migrate_task() 

There were 3 invocations of task_hot() in can_migrate_task().

Replace these 3 invocations by only one invocation, cached in
a local variable.

Signed-off-by: Luis Henriques <henrix@sapo.pt>
LKML-Reference: <20090316195902.GA6197@hades.domain.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Luis Henriques 2009-03-16 19:59:02 +00:00 committed by Ingo Molnar
parent 80dd99b368
commit 708dc51253
1 changed files with 6 additions and 4 deletions
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10
kernel/sched.c
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@ -3002,6 +3002,7 @@ 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
@ -3025,10 +3026,11 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
* 2) too many balance attempts have failed.
*/
if (!task_hot(p, rq->clock, sd) ||
sd->nr_balance_failed > sd->cache_nice_tries) {
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 (task_hot(p, rq->clock, sd)) {
if (tsk_cache_hot) {
schedstat_inc(sd, lb_hot_gained[idle]);
schedstat_inc(p, se.nr_forced_migrations);
}
@ -3036,7 +3038,7 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu,
return 1;
}
if (task_hot(p, rq->clock, sd)) {
if (tsk_cache_hot) {
schedstat_inc(p, se.nr_failed_migrations_hot);
return 0;
}