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| author | Vincent Donnefort <vincent.donnefort@arm.com> | 2021-11-29 20:31:15 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-12-04 12:56:21 +0300 |
| commit | 014ba44e8184e1acf93e0cbb7089ee847802f8f0 (patch) | |
| tree | 2680c0e5c95ac8837e9bcd3d27cf9f02100b270c /kernel/sched | |
| parent | 8b4e74ccb582797f6f0b0a50372ebd9fd2372a27 (diff) | |
| download | linux-014ba44e8184e1acf93e0cbb7089ee847802f8f0.tar.xz | |
sched/fair: Fix per-CPU kthread and wakee stacking for asym CPU capacity
select_idle_sibling() has a special case for tasks woken up by a per-CPU
kthread where the selected CPU is the previous one. For asymmetric CPU
capacity systems, the assumption was that the wakee couldn't have a
bigger utilization during task placement than it used to have during the
last activation. That was not considering uclamp.min which can completely
change between two task activations and as a consequence mandates the
fitness criterion asym_fits_capacity(), even for the exit path described
above.
Fixes: b4c9c9f15649 ("sched/fair: Prefer prev cpu in asymmetric wakeup path")
Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lkml.kernel.org/r/20211129173115.4006346-1-vincent.donnefort@arm.com
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/fair.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 5cd27986b43e..06722188df49 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6400,7 +6400,8 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) if (is_per_cpu_kthread(current) && in_task() && prev == smp_processor_id() && - this_rq()->nr_running <= 1) { + this_rq()->nr_running <= 1 && + asym_fits_capacity(task_util, prev)) { return prev; } |