[PATCH] sched: fix SMT scheduler bug
The SMT scheduler incorrectly skips kernel threads even if they are runnable (but they are preempted by a higher-prio user-space task which got SMT-delayed by an even higher-priority task running on a sibling CPU). Fix this for now by only doing the SMT-nice optimization if the to-be-delayed task is the only runnable task. (This should cover most of the real-life cases anyway.) This bug has been in the SMT scheduler since 2.6.17 or so, but has only been noticed now by the active check in the dynticks code. Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Michal Piotrowski <michal.k.k.piotrowski@gmail.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Родитель
3f555c700b
Коммит
7355690ead
|
@ -3547,7 +3547,7 @@ need_resched_nonpreemptible:
|
|||
}
|
||||
}
|
||||
next->sleep_type = SLEEP_NORMAL;
|
||||
if (dependent_sleeper(cpu, rq, next))
|
||||
if (rq->nr_running == 1 && dependent_sleeper(cpu, rq, next))
|
||||
next = rq->idle;
|
||||
switch_tasks:
|
||||
if (next == rq->idle)
|
||||
|
|
Загрузка…
Ссылка в новой задаче