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SubjectRe: [RFC PATCH] tick/sched: update full_nohz status after SCHED dep is cleared
On Wed, May 20, 2020 at 08:47:10PM +0200, Juri Lelli wrote:
> On 20/05/20 19:02, Frederic Weisbecker wrote:
> > 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:
>
> I run with
>
> trace-cmd record -e sched_switch -e sched_wakeup -e sched_migrate_task \
> -e 'timer:*' -e 'irq_vectors:*' -e 'irq:softirq*' \
> -e 'irq:irq_handler*' taskset --cpu-list 4-35 ./sysjitter/sysjitter \
> --runtime 10 200
>
> And
>
> $ grep ' timer_expire_entry:' trace.txt | wc -l
> 1173
>
> seems to confirm that the event was indeed enabled, e.g.
>
> ksoftirqd/11-100 [011] 159.270023: timer_expire_entry: timer=0xffff9807df8a5a60 function=delayed_work_timer_fn now=4294826418 baseclk=4294825984

That's interesting! I'll see if I can reproduce that with threaded irqs. If not we'll
have to investigate on your machine. We really don't want to trigger timer softirqs
when it's not necessary.

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