From: Mike Galbraith <efault@gmx.de>
To: "g.medini" <g.medini@eurosoft.it>
Cc: RT <linux-rt-users@vger.kernel.org>
Subject: Re: High latency of a system based on 5.19 rt
Date: Tue, 26 Sep 2023 09:04:59 +0200 [thread overview]
Message-ID: <f9fd60d19937c4e22407738f2d78b3ca4a7887d8.camel@gmx.de> (raw)
In-Reply-To: <S1JV78$805284328FE38E68AC9E7D23F35846D8@eurosoft.it>
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.
Trace starting at 37us vs 0 makes me suspect box wasn't being all it
can be at the time. Dunno if that's the case, but I'd suggest taking
cpufreq out of the picture when latency source hunting in general.
-Mike
next prev parent reply other threads:[~2023-09-26 7:05 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 [this message]
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
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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