Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
sched/hrtick: Avoid tiny hrtick rearms
Tiny adjustments to the hrtick expiry time below 5 microseconds are just
causing extra work for no real value. Filter them out when restarting the
hrtick.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163429.340593047@kernel.org
authored by
Thomas Gleixner
and committed by
Peter Zijlstra
c8cdb9b5
96d1610e
+19
-5
+19
-5
kernel/sched/core.c
+19
-5
kernel/sched/core.c
···
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903
return HRTIMER_NORESTART;
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904
}
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906
-
static void __hrtick_restart(struct rq *rq)
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+
static inline bool hrtick_needs_rearm(struct hrtimer *timer, ktime_t expires)
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+
{
908
+
/*
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+
* Queued is false when the timer is not started or currently
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+
* running the callback. In both cases, restart. If queued check
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+
* whether the expiry time actually changes substantially.
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+
*/
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+
return !hrtimer_is_queued(timer) ||
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+
abs(expires - hrtimer_get_expires(timer)) > 5000;
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+
}
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+
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+
static void hrtick_cond_restart(struct rq *rq)
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{
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struct hrtimer *timer = &rq->hrtick_timer;
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ktime_t time = rq->hrtick_time;
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911
-
hrtimer_start(timer, time, HRTIMER_MODE_ABS_PINNED_HARD);
922
+
if (hrtick_needs_rearm(timer, time))
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+
hrtimer_start(timer, time, HRTIMER_MODE_ABS_PINNED_HARD);
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}
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/*
···
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struct rq_flags rf;
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rq_lock(rq, &rf);
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-
__hrtick_restart(rq);
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+
hrtick_cond_restart(rq);
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rq_unlock(rq, &rf);
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}
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···
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}
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951
964
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rq->hrtick_time = ktime_add_ns(ktime_get(), delta);
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+
if (!hrtick_needs_rearm(&rq->hrtick_timer, rq->hrtick_time))
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+
return;
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if (rq == this_rq())
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-
__hrtick_restart(rq);
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+
hrtimer_start(&rq->hrtick_timer, rq->hrtick_time, HRTIMER_MODE_ABS_PINNED_HARD);
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else
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smp_call_function_single_async(cpu_of(rq), &rq->hrtick_csd);
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}
···
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{
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if (rq->hrtick_sched & HRTICK_SCHED_START) {
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rq->hrtick_time = ktime_add_ns(ktime_get(), rq->hrtick_delay);
983
-
__hrtick_restart(rq);
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+
hrtick_cond_restart(rq);
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} else if (idle_rq(rq)) {
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/*
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* No need for using hrtimer_is_active(). The timer is CPU local