From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Mike Galbraith <efault@gmx.de>
Cc: Clark Williams <williams@redhat.com>,
"g.medini" <g.medini@eurosoft.it>,
RT <linux-rt-users@vger.kernel.org>
Subject: Re: High latency of a system based on 5.19 rt
Date: Mon, 2 Oct 2023 12:05:42 +0200 [thread overview]
Message-ID: <20231002100542.59fbxJ0f@linutronix.de> (raw)
In-Reply-To: <8eb75f2118086edf828ac059999fd52b64382576.camel@gmx.de>
On 2023-09-26 15:15:46 [+0200], Mike Galbraith wrote:
> On Tue, 2023-09-26 at 12:30 +0000, Clark Williams wrote:
> > On Tue, Sep 26, 2023 at 7:05 AM Mike Galbraith <efault@gmx.de> wrote:
> > > On Mon, 2023-09-25 at 18:30 +0200, g.medini@eurosoft.it wrote:
> > > > # tracer: wakeup_rt
> > > > #
> > > > # wakeup_rt latency trace v1.1.5 on 5.19.0-rt10
> > > > # --------------------------------------------------------------------
> > > > # latency: 357 us, #401/401, CPU#0 | (M:preempt_rt VP:0, KP:0, SP:0 HP:0 #P:2)
> > > > # -----------------
> > > > # | task: ktimers/0-15 (uid:0 nice:0 policy:1 rt_prio:1)
> > > > # -----------------
> > >
> > > The first thing that pokes me in the eye is that priority. I'd bump
> > > that a lot. As it sits, anything high priority ktimers may wake when
> > > it finally gets the CPU gets to enjoy all the latency ktimers is eating
> > > in this trace due to it having been deemed relatively unimportant.
> >
> > Hmmm, IRQs are running at FIFO:50 by default. Do we want the ktimer
> > running above the IRQ service thread?
>
> I think so yeah, quick like bunny wakeup resource should punch through.
Why not perform all wakes from hardirq then? If SCHED_OTHER is so
important…
> -Mike
Sebastian
next prev parent reply other threads:[~2023-10-02 10:05 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-25 16:30 High latency of a system based on 5.19 rt g.medini
2023-09-25 17:02 ` Ralf Mardorf
2023-09-26 7:04 ` Mike Galbraith
2023-09-26 12:34 ` Clark Williams
[not found] ` <CAMLffL8=zW0Bv47R=r3=Lh9==OjDrM=FTJZgmm6PYGOyTedeBA@mail.gmail.com>
2023-09-26 13:15 ` Mike Galbraith
2023-10-02 10:05 ` Sebastian Andrzej Siewior [this message]
2023-10-02 11:58 ` Mike Galbraith
2023-10-02 14:16 ` Sebastian Andrzej Siewior
2023-10-02 15:20 ` Mike Galbraith
2023-10-02 10:02 ` Sebastian Andrzej Siewior
-- strict thread matches above, loose matches on Subject: below --
2023-10-03 13:47 g.medini
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