summaryrefslogtreecommitdiff
path: root/kernel/sched
diff options
context:
space:
mode:
authorCheng Chao <cs.os.kernel@gmail.com>2016-09-14 10:01:50 +0800
committerIngo Molnar <mingo@kernel.org>2016-09-22 14:53:45 +0200
commitbf89a304722f6904009499a31dc68ab9a5c9742e (patch)
tree2177d0136fa62ca04091b6f5823ad32b055bbf7c /kernel/sched
parent0b8473570ce1af3e80da05b59f9321f30253de4d (diff)
stop_machine: Avoid a sleep and wakeup in stop_one_cpu()
In case @cpu == smp_proccessor_id(), we can avoid a sleep+wakeup cycle by doing a preemption. Callers such as sched_exec() can benefit from this change. Signed-off-by: Cheng Chao <cs.os.kernel@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akpm@linux-foundation.org Cc: chris@chris-wilson.co.uk Cc: tj@kernel.org Link: http://lkml.kernel.org/r/1473818510-6779-1-git-send-email-cs.os.kernel@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/core.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index c5f020c601b2..ff4e3c066dc2 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1063,8 +1063,12 @@ static int migration_cpu_stop(void *data)
* holding rq->lock, if p->on_rq == 0 it cannot get enqueued because
* we're holding p->pi_lock.
*/
- if (task_rq(p) == rq && task_on_rq_queued(p))
- rq = __migrate_task(rq, p, arg->dest_cpu);
+ if (task_rq(p) == rq) {
+ if (task_on_rq_queued(p))
+ rq = __migrate_task(rq, p, arg->dest_cpu);
+ else
+ p->wake_cpu = arg->dest_cpu;
+ }
raw_spin_unlock(&rq->lock);
raw_spin_unlock(&p->pi_lock);