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sched: Fix CACHE_HOT_BUDY condition 

When computing cache hot, we should check if the migration dst cpu is idle,
instead of the current cpu. Though they are same in normal balancing, that
is false nowadays in nohz idle balancing at least.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Mike Galbraith <mgalbraith@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140607090452.4696E301D2@webmail.sinamail.sina.com.cn
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Hillf Danton 2014-06-10 10:58:43 +02:00 committed by Ingo Molnar
parent bb97fc3164
commit 5d5e2b1bcb
1 changed files with 4 additions and 5 deletions
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9
kernel/sched/fair.c
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@ -5095,8 +5095,7 @@ static void move_task(struct task_struct *p, struct lb_env *env)
/*
* Is this task likely cache-hot:
*/
static int
task_hot(struct task_struct *p, u64 now)
static int task_hot(struct task_struct *p, struct lb_env *env)
{
s64 delta;
@ -5109,7 +5108,7 @@ task_hot(struct task_struct *p, u64 now)
/*
* Buddy candidates are cache hot:
*/
if (sched_feat(CACHE_HOT_BUDDY) && this_rq()->nr_running &&
if (sched_feat(CACHE_HOT_BUDDY) && env->dst_rq->nr_running &&
(&p->se == cfs_rq_of(&p->se)->next ||
&p->se == cfs_rq_of(&p->se)->last))
return 1;
@ -5119,7 +5118,7 @@ task_hot(struct task_struct *p, u64 now)
if (sysctl_sched_migration_cost == 0)
return 0;
delta = now - p->se.exec_start;
delta = rq_clock_task(env->src_rq) - p->se.exec_start;
return delta < (s64)sysctl_sched_migration_cost;
}
@ -5273,7 +5272,7 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
* 2) task is cache cold, or
* 3) too many balance attempts have failed.
*/
tsk_cache_hot = task_hot(p, rq_clock_task(env->src_rq));
tsk_cache_hot = task_hot(p, env);
if (!tsk_cache_hot)
tsk_cache_hot = migrate_degrades_locality(p, env);