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| author | Libo Chen <libo.chen@oracle.com> | 2022-08-10 15:33:13 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-05-11 23:00:34 +0900 |
| commit | 3e09b68fc520a60cc634428d93e42cee4f00513c (patch) | |
| tree | 610e9c71d4052cf278ebc13b9edc2129358f0891 /kernel | |
| parent | c3b9f95598b8029b7e8d9a6b3ad14280e712c70c (diff) | |
| download | linux-stable-3e09b68fc520a60cc634428d93e42cee4f00513c.tar.gz linux-stable-3e09b68fc520a60cc634428d93e42cee4f00513c.tar.bz2 linux-stable-3e09b68fc520a60cc634428d93e42cee4f00513c.zip | |
sched/fair: Fix inaccurate tally of ttwu_move_affine
[ Upstream commit 39afe5d6fc59237ff7738bf3ede5a8856822d59d ]
There are scenarios where non-affine wakeups are incorrectly counted as
affine wakeups by schedstats.
When wake_affine_idle() returns prev_cpu which doesn't equal to
nr_cpumask_bits, it will slip through the check: target == nr_cpumask_bits
in wake_affine() and be counted as if target == this_cpu in schedstats.
Replace target == nr_cpumask_bits with target != this_cpu to make sure
affine wakeups are accurately tallied.
Fixes: 806486c377e33 (sched/fair: Do not migrate if the prev_cpu is idle)
Suggested-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Libo Chen <libo.chen@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Link: https://lore.kernel.org/r/20220810223313.386614-1-libo.chen@oracle.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/fair.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 2dd67e212f0a..646a6ae4b250 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6207,7 +6207,7 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, target = wake_affine_weight(sd, p, this_cpu, prev_cpu, sync); schedstat_inc(p->stats.nr_wakeups_affine_attempts); - if (target == nr_cpumask_bits) + if (target != this_cpu) return prev_cpu; schedstat_inc(sd->ttwu_move_affine); |