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| author | Qais Yousef <qais.yousef@arm.com> | 2021-01-19 15:07:55 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-01-27 19:26:42 +0300 |
| commit | 0ae78eec8aa64e645866e75005162603a77a0f49 (patch) | |
| tree | 7bc9ed23a0d7351645204ff9023197fe236bfd85 /kernel/sched | |
| parent | 65bcf072e20ed7597caa902f170f293662b0af3c (diff) | |
| download | linux-0ae78eec8aa64e645866e75005162603a77a0f49.tar.xz | |
sched/eas: Don't update misfit status if the task is pinned
If the task is pinned to a cpu, setting the misfit status means that
we'll unnecessarily continuously attempt to migrate the task but fail.
This continuous failure will cause the balance_interval to increase to
a high value, and eventually cause unnecessary significant delays in
balancing the system when real imbalance happens.
Caught while testing uclamp where rt-app calibration loop was pinned to
cpu 0, shortly after which we spawn another task with high util_clamp
value. The task was failing to migrate after over 40ms of runtime due to
balance_interval unnecessary expanded to a very high value from the
calibration loop.
Not done here, but it could be useful to extend the check for pinning to
verify that the affinity of the task has a cpu that fits. We could end
up in a similar situation otherwise.
Fixes: 3b1baa6496e6 ("sched/fair: Add 'group_misfit_task' load-balance type")
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Quentin Perret <qperret@google.com>
Acked-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20210119120755.2425264-1-qais.yousef@arm.com
Diffstat (limited to 'kernel/sched')
| -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 197a51473e0c..9379a481dd8c 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4060,7 +4060,7 @@ static inline void update_misfit_status(struct task_struct *p, struct rq *rq) if (!static_branch_unlikely(&sched_asym_cpucapacity)) return; - if (!p) { + if (!p || p->nr_cpus_allowed == 1) { rq->misfit_task_load = 0; return; } |