Commit-ID: 708dc5125309cd33c5daaad3026cc4ae6ef39c8b
Gitweb: http://git.kernel.org/tip/708dc5125309cd33c5daaad3026cc4ae6ef39c8b
Author: Luis Henriques <henrix@xxxxxxx>
AuthorDate: Mon, 16 Mar 2009 19:59:02 +0000
Commit: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Tue, 17 Mar 2009 12:04:41 +0100
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@xxxxxxx>
LKML-Reference: <20090316195902.GA6197@xxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
kernel/sched.c | 10 ++++++----
1 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c
index 489e7d9..d2dfe4c 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -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;
}
--
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