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56 lines
2.1 KiB
Diff
56 lines
2.1 KiB
Diff
From: "Ahmed S. Darwish" <a.darwish@linutronix.de>
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Date: Mon, 9 Mar 2020 18:15:29 +0000
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Subject: [PATCH] time/sched_clock: Expire timer in hardirq context
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To minimize latency, PREEMPT_RT kernels expires hrtimers in preemptible
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softirq context by default. This can be overriden by marking the timer's
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expiry with HRTIMER_MODE_HARD.
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sched_clock_timer is missing this annotation: if its callback is preempted
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and the duration of the preemption exceeds the wrap around time of the
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underlying clocksource, sched clock will get out of sync.
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Mark the sched_clock_timer for expiry in hard interrupt context.
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Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Link: https://lkml.kernel.org/r/20200309181529.26558-1-a.darwish@linutronix.de
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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kernel/time/sched_clock.c | 9 +++++----
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1 file changed, 5 insertions(+), 4 deletions(-)
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--- a/kernel/time/sched_clock.c
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+++ b/kernel/time/sched_clock.c
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@@ -207,7 +207,8 @@ sched_clock_register(u64 (*read)(void),
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if (sched_clock_timer.function != NULL) {
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/* update timeout for clock wrap */
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- hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL);
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+ hrtimer_start(&sched_clock_timer, cd.wrap_kt,
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+ HRTIMER_MODE_REL_HARD);
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}
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r = rate;
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@@ -251,9 +252,9 @@ void __init generic_sched_clock_init(voi
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* Start the timer to keep sched_clock() properly updated and
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* sets the initial epoch.
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*/
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- hrtimer_init(&sched_clock_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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+ hrtimer_init(&sched_clock_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
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sched_clock_timer.function = sched_clock_poll;
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- hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL);
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+ hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL_HARD);
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}
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/*
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@@ -290,7 +291,7 @@ void sched_clock_resume(void)
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struct clock_read_data *rd = &cd.read_data[0];
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rd->epoch_cyc = cd.actual_read_sched_clock();
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- hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL);
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+ hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL_HARD);
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rd->read_sched_clock = cd.actual_read_sched_clock;
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}
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