diff options
| author | Vincent Guittot <vincent.guittot@linaro.org> | 2026-04-10 15:23:21 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-04-10 16:31:50 +0200 |
| commit | 78cde54ea5f03398f1cf6656de2472068f6da966 (patch) | |
| tree | d49b61af0d85b0bbb69d23a5c6c924bfbcd0f225 /kernel | |
| parent | 985215804dcbf02ab675977e770708e3f084e9fc (diff) | |
sched/eevdf: Clear buddies for preempt_short
next buddy should not prevent shorter slice preemption. Don't take buddy
into account when checking if shorter slice entity can preempt and clear it
if the entity with a shorter slice can preempt current.
Test on snapdragon rb5:
hackbench -T -p -l 16000000 -g 2 1> /dev/null &
hackbench runs in cgroup /test-A
cyclictest -t 1 -i 2777 -D 63 --policy=fair --mlock -h 20000 -q
cyclictest runs in cgroup /test-B
tip/sched/core tip/sched/core +this patch
cyclictest slice (ms) (default)2.8 8 8
hackbench slice (ms) (default)2.8 20 20
Total Samples | 22679 22595 22686
Average (us) | 84 94(-12%) 59( 37%)
Median (P50) (us) | 56 56( 0%) 56( 0%)
90th Percentile (us) | 64 65(- 2%) 63( 3%)
99th Percentile (us) | 1047 1273(-22%) 74( 94%)
99.9th Percentile (us) | 2431 4751(-95%) 663( 86%)
Maximum (us) | 4694 8655(-84%) 3934( 55%)
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260410132321.2897789-1-vincent.guittot@linaro.org
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/fair.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 12890ef16603..f179faf7a6a1 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1116,7 +1116,7 @@ static struct sched_entity *__pick_eevdf(struct cfs_rq *cfs_rq, bool protect) /* * Picking the ->next buddy will affect latency but not fairness. */ - if (sched_feat(PICK_BUDDY) && + if (sched_feat(PICK_BUDDY) && protect && cfs_rq->next && entity_eligible(cfs_rq, cfs_rq->next)) { /* ->next will never be delayed */ WARN_ON_ONCE(cfs_rq->next->sched_delayed); @@ -9138,8 +9138,10 @@ pick: return; preempt: - if (preempt_action == PREEMPT_WAKEUP_SHORT) + if (preempt_action == PREEMPT_WAKEUP_SHORT) { cancel_protect_slice(se); + clear_buddies(cfs_rq, se); + } resched_curr_lazy(rq); } |