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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: Thu, 21 May 2020 02:44:44 +0200
Message-ID: <20200521004443.GB15455@lenoir> (raw)
In-Reply-To: <20200520184710.GO10078@localhost.localdomain>

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.

  reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-20 14:04 Juri Lelli
2020-05-20 16:24 ` Frederic Weisbecker
2020-05-20 16:49   ` Juri Lelli
2020-05-20 17:02     ` Frederic Weisbecker
2020-05-20 18:47       ` Juri Lelli
2020-05-21  0:44         ` Frederic Weisbecker [this message]
2020-05-21 17:00           ` Juri Lelli

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