* [PATCH 2/2 -tip] sched: small optimisation on can_migrate_task
@ 2009-03-16 19:59 Luis Henriques
2009-03-17 11:06 ` [tip:sched/cleanups] sched: small optimisation of can_migrate_task() Luis Henriques
0 siblings, 1 reply; 2+ messages in thread
From: Luis Henriques @ 2009-03-16 19:59 UTC (permalink / raw)
To: Ingo Molnar; +Cc: linux-kernel
There were 3 invocation to task_hot() in function can_migrate_task(). These 3
invocations have been replaced by only one invocation, cached in a local
variable.
Signed-off-by: Luis Henriques <henrix@sapo.pt>
---
kernel/sched.c | 10 ++++++----
1 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c
index 0a5d929..4000304 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3072,6 +3072,7 @@ 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
@@ -3095,10 +3096,11 @@ 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);
}
@@ -3106,7 +3108,7 @@ 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;
}
--
1.6.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [tip:sched/cleanups] sched: small optimisation of can_migrate_task()
2009-03-16 19:59 [PATCH 2/2 -tip] sched: small optimisation on can_migrate_task Luis Henriques
@ 2009-03-17 11:06 ` Luis Henriques
0 siblings, 0 replies; 2+ messages in thread
From: Luis Henriques @ 2009-03-17 11:06 UTC (permalink / raw)
To: linux-tip-commits; +Cc: linux-kernel, hpa, mingo, henrix, tglx, mingo
Commit-ID: 708dc5125309cd33c5daaad3026cc4ae6ef39c8b
Gitweb: http://git.kernel.org/tip/708dc5125309cd33c5daaad3026cc4ae6ef39c8b
Author: Luis Henriques <henrix@sapo.pt>
AuthorDate: Mon, 16 Mar 2009 19:59:02 +0000
Commit: Ingo Molnar <mingo@elte.hu>
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@sapo.pt>
LKML-Reference: <20090316195902.GA6197@hades.domain.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
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;
}
^ permalink raw reply related [flat|nested] 2+ messages in thread
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