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| author | Vincent Donnefort <vincent.donnefort@arm.com> | 2021-11-29 20:31:15 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-01-27 13:03:27 +0300 |
| commit | d3c4b3c801c0f13deef2b04d7d93dac338dd9552 (patch) | |
| tree | b636c371df897e4e9120a26955a9878c615be941 /kernel/sched | |
| parent | 00c10519538fd739312a9ee3acdee264873e126e (diff) | |
| download | linux-d3c4b3c801c0f13deef2b04d7d93dac338dd9552.tar.xz | |
sched/fair: Fix per-CPU kthread and wakee stacking for asym CPU capacity
[ Upstream commit 014ba44e8184e1acf93e0cbb7089ee847802f8f0 ]
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
Signed-off-by: Sasha Levin <sashal@kernel.org>
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 c6cb8832796b..d41f966f5866 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6431,7 +6431,8 @@ 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; } |