diff options
| author | Ahmed S. Darwish <a.darwish@linutronix.de> | 2020-03-09 18:15:29 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-04-17 10:50:02 +0200 |
| commit | 2902207377f8b725d34be7d0a85c446b339792c7 (patch) | |
| tree | be623fe664b4e772c2861184568dfc45493f3d10 /kernel/time | |
| parent | 3f755f5233a2a046842f22bcce167dfea4ce1909 (diff) | |
time/sched_clock: Expire timer in hardirq context
[ Upstream commit 2c8bd58812ee3dbf0d78b566822f7eacd34bdd7b ]
To minimize latency, PREEMPT_RT kernels expires hrtimers in preemptible
softirq context by default. This can be overriden by marking the timer's
expiry with HRTIMER_MODE_HARD.
sched_clock_timer is missing this annotation: if its callback is preempted
and the duration of the preemption exceeds the wrap around time of the
underlying clocksource, sched clock will get out of sync.
Mark the sched_clock_timer for expiry in hard interrupt context.
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200309181529.26558-1-a.darwish@linutronix.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel/time')
| -rw-r--r-- | kernel/time/sched_clock.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c index dbd69052eaa6..a5538dd76a81 100644 --- a/kernel/time/sched_clock.c +++ b/kernel/time/sched_clock.c @@ -207,7 +207,8 @@ sched_clock_register(u64 (*read)(void), int bits, unsigned long rate) if (sched_clock_timer.function != NULL) { /* update timeout for clock wrap */ - hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL); + hrtimer_start(&sched_clock_timer, cd.wrap_kt, + HRTIMER_MODE_REL_HARD); } r = rate; @@ -251,9 +252,9 @@ void __init generic_sched_clock_init(void) * Start the timer to keep sched_clock() properly updated and * sets the initial epoch. */ - hrtimer_init(&sched_clock_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + hrtimer_init(&sched_clock_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); sched_clock_timer.function = sched_clock_poll; - hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL); + hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL_HARD); } /* @@ -290,7 +291,7 @@ void sched_clock_resume(void) struct clock_read_data *rd = &cd.read_data[0]; rd->epoch_cyc = cd.actual_read_sched_clock(); - hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL); + hrtimer_start(&sched_clock_timer, cd.wrap_kt, HRTIMER_MODE_REL_HARD); rd->read_sched_clock = cd.actual_read_sched_clock; } |