diff options
| author | John Stultz <jstultz@google.com> | 2025-04-29 08:07:26 -0700 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2025-04-30 14:45:41 +0200 |
| commit | b7ca5743a2604156d6083b88cefacef983f3a3a6 (patch) | |
| tree | 6161a960a530de7ba3db9fde196f9377ebaa224a | |
| parent | c70fc32f44431bb30f9025ce753ba8be25acbba3 (diff) | |
| download | queue-sched/core.tar.gz | |
sched/core: Tweak wait_task_inactive() to force dequeue sched_delayed taskssched/core
It was reported that in 6.12, smpboot_create_threads() was
taking much longer then in 6.6.
I narrowed down the call path to:
smpboot_create_threads()
-> kthread_create_on_cpu()
-> kthread_bind()
-> __kthread_bind_mask()
->wait_task_inactive()
Where in wait_task_inactive() we were regularly hitting the
queued case, which sets a 1 tick timeout, which when called
multiple times in a row, accumulates quickly into a long
delay.
I noticed disabling the DELAY_DEQUEUE sched feature recovered
the performance, and it seems the newly create tasks are usually
sched_delayed and left on the runqueue.
So in wait_task_inactive() when we see the task
p->se.sched_delayed, manually dequeue the sched_delayed task
with DEQUEUE_DELAYED, so we don't have to constantly wait a
tick.
Fixes: 152e11f6df29 ("sched/fair: Implement delayed dequeue")
Reported-by: peter-yc.chang@mediatek.com
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lkml.kernel.org/r/20250429150736.3778580-1-jstultz@google.com
| -rw-r--r-- | kernel/sched/core.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 79692f85643fee..a3507ed58424f2 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2283,6 +2283,12 @@ unsigned long wait_task_inactive(struct task_struct *p, unsigned int match_state * just go back and repeat. */ rq = task_rq_lock(p, &rf); + /* + * If task is sched_delayed, force dequeue it, to avoid always + * hitting the tick timeout in the queued case + */ + if (p->se.sched_delayed) + dequeue_task(rq, p, DEQUEUE_SLEEP | DEQUEUE_DELAYED); trace_sched_wait_task(p); running = task_on_cpu(rq, p); queued = task_on_rq_queued(p); |