From: Frederic Weisbecker <frederic@kernel.org>
To: Juri Lelli <juri.lelli@redhat.com>
Cc: fweisbec@gmail.com, tglx@linutronix.de, mingo@kernel.org,
linux-rt-users@vger.kernel.org, peterz@infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] tick/sched: update full_nohz status after SCHED dep is cleared
Date: Wed, 20 May 2020 19:02:16 +0200 [thread overview]
Message-ID: <20200520170215.GB8800@lenoir> (raw)
In-Reply-To: <20200520164925.GM10078@localhost.localdomain>
On Wed, May 20, 2020 at 06:49:25PM +0200, Juri Lelli wrote:
> On 20/05/20 18:24, Frederic Weisbecker wrote:
>
> Hummm, so I enabled 'timer:*', anything else you think I should be
> looking at?
Are you sure you also enabled timer_expire_entry?
Because:
>
> ...
> ksoftirqd/13-117 [013] 148.265945: softirq_entry: vec=1 [action=TIMER]
...the timer softirq keep triggering without any timer callback executed. If that's the
case, we may be dealing with an interesting issue.
Thanks.
> ksoftirqd/13-117 [013] 148.265947: softirq_exit: vec=1 [action=TIMER]
> ksoftirqd/13-117 [013] 148.265948: softirq_entry: vec=7 [action=SCHED]
> ksoftirqd/13-117 [013] 148.265950: softirq_exit: vec=7 [action=SCHED]
> ksoftirqd/13-117 [013] 148.265952: sched_switch: ksoftirqd/13:117 [120] S ==> sysjitter:2536 [120]
> sysjitter-2536 [013] 148.266912: local_timer_entry: vector=236
> sysjitter-2536 [013] 148.266914: hrtimer_cancel: hrtimer=0xffff9807df91bee0
> sysjitter-2536 [013] 148.266916: hrtimer_expire_entry: hrtimer=0xffff9807df91bee0 now=148249107837 function=tick_sched_timer/0x0
> sysjitter-2536 [013] 148.266918: softirq_raise: vec=1 [action=TIMER]
> sysjitter-2536 [013] 148.266920: softirq_raise: vec=7 [action=SCHED]
> sysjitter-2536 [013] 148.266922: hrtimer_expire_exit: hrtimer=0xffff9807df91bee0
> sysjitter-2536 [013] 148.266924: hrtimer_start: hrtimer=0xffff9807df91bee0 function=tick_sched_timer/0x0 expires=148250105422 softexpires=148250105422
> sysjitter-2536 [013] 148.266926: local_timer_exit: vector=236
> sysjitter-2536 [013] 148.266930: sched_wakeup: ksoftirqd/13:117 [120] success=1 CPU:013
> sysjitter-2536 [013] 148.266932: tick_stop: success=0 dependency=SCHED
> sysjitter-2536 [013] 148.266934: irq_work_entry: vector=246
> sysjitter-2536 [013] 148.266936: irq_work_exit: vector=246
> sysjitter-2536 [013] 148.266937: tick_stop: success=0 dependency=SCHED
> sysjitter-2536 [013] 148.266940: sched_switch: sysjitter:2536 [120] R ==> ksoftirqd/13:117 [120]
> ksoftirqd/13-117 [013] 148.266943: softirq_entry: vec=1 [action=TIMER]
> ksoftirqd/13-117 [013] 148.266946: softirq_exit: vec=1 [action=TIMER]
> ksoftirqd/13-117 [013] 148.266946: softirq_entry: vec=7 [action=SCHED]
> ksoftirqd/13-117 [013] 148.266948: softirq_exit: vec=7 [action=SCHED]
> ksoftirqd/13-117 [013] 148.266950: sched_switch: ksoftirqd/13:117 [120] S ==> sysjitter:2536 [120]
> sysjitter-2536 [013] 148.267912: local_timer_entry: vector=236
> sysjitter-2536 [013] 148.267914: hrtimer_cancel: hrtimer=0xffff9807df91bee0
> sysjitter-2536 [013] 148.267916: hrtimer_expire_entry: hrtimer=0xffff9807df91bee0 now=148250107750 function=tick_sched_timer/0x0
> sysjitter-2536 [013] 148.267918: softirq_raise: vec=1 [action=TIMER]
> sysjitter-2536 [013] 148.267920: softirq_raise: vec=7 [action=SCHED]
> sysjitter-2536 [013] 148.267922: hrtimer_expire_exit: hrtimer=0xffff9807df91bee0
> sysjitter-2536 [013] 148.267924: hrtimer_start: hrtimer=0xffff9807df91bee0 function=tick_sched_timer/0x0 expires=148251105422 softexpires=148251105422
> sysjitter-2536 [013] 148.267926: local_timer_exit: vector=236
> sysjitter-2536 [013] 148.267929: sched_wakeup: ksoftirqd/13:117 [120] success=1 CPU:013
> sysjitter-2536 [013] 148.267931: tick_stop: success=0 dependency=SCHED
> sysjitter-2536 [013] 148.267934: irq_work_entry: vector=246
> sysjitter-2536 [013] 148.267936: irq_work_exit: vector=246
> sysjitter-2536 [013] 148.267937: tick_stop: success=0 dependency=SCHED
> sysjitter-2536 [013] 148.267940: sched_switch: sysjitter:2536 [120] R ==> ksoftirqd/13:117 [120]
> ksoftirqd/13-117 [013] 148.267943: softirq_entry: vec=1 [action=TIMER]
> ksoftirqd/13-117 [013] 148.267945: softirq_exit: vec=1 [action=TIMER]
> ksoftirqd/13-117 [013] 148.267946: softirq_entry: vec=7 [action=SCHED]
> ksoftirqd/13-117 [013] 148.267947: softirq_exit: vec=7 [action=SCHED]
> ksoftirqd/13-117 [013] 148.267949: sched_switch: ksoftirqd/13:117 [120] S ==> sysjitter:2536 [120]
> sysjitter-2536 [013] 148.268865: call_function_single_entry: vector=251
> sysjitter-2536 [013] 148.268867: call_function_single_exit: vector=251
> sysjitter-2536 [013] 148.268870: tick_stop: success=1 dependency=NONE
> sysjitter-2536 [013] 148.268872: hrtimer_cancel: hrtimer=0xffff9807df91bee0
> sysjitter-2536 [013] 148.268876: call_function_single_entry: vector=251
> sysjitter-2536 [013] 148.268878: call_function_single_exit: vector=251
> ...
>
> it looks like tick sched timer is kept armed until tick_stop
> succedes (because of the check performed after _single_exit)?
>
> Thanks for your quick reply!
>
next prev parent reply other threads:[~2020-05-20 17:02 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-20 14:04 [RFC PATCH] tick/sched: update full_nohz status after SCHED dep is cleared Juri Lelli
2020-05-20 16:24 ` Frederic Weisbecker
2020-05-20 16:49 ` Juri Lelli
2020-05-20 17:02 ` Frederic Weisbecker [this message]
2020-05-20 18:47 ` Juri Lelli
2020-05-21 0:44 ` Frederic Weisbecker
2020-05-21 17:00 ` Juri Lelli
2020-06-15 15:05 ` Juri Lelli
2020-06-15 21:07 ` Frederic Weisbecker
2020-06-16 6:57 ` Juri Lelli
2020-06-16 20:46 ` Frederic Weisbecker
2020-06-29 12:36 ` Juri Lelli
2020-06-29 12:42 ` Frederic Weisbecker
2020-06-29 12:53 ` Juri Lelli
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