From: John Ogness <john.ogness@linutronix.de>
To: Marc Gonzalez <marc.w.gonzalez@free.fr>, linux-rt-users@vger.kernel.org
Cc: Daniel Wagner <dwagner@suse.de>,
Leon Woestenberg <leon@sidebranch.com>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Clark Williams <williams@redhat.com>,
Pavel Machek <pavel@denx.de>,
Luis Goncalves <lgoncalv@redhat.com>,
John McCalpin <mccalpin@tacc.utexas.edu>,
Frederic Weisbecker <fweisbec@gmail.com>,
Ingo Molnar <mingo@kernel.org>,
Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: Unexplained variance in run-time of trivial program
Date: Tue, 09 Sep 2025 14:40:57 +0206 [thread overview]
Message-ID: <84ms73kdn2.fsf@jogness.linutronix.de> (raw)
In-Reply-To: <0d87e3c3-8de1-4d98-802e-a292f63f1bf1@free.fr>
On 2025-09-09, Marc Gonzalez <marc.w.gonzalez@free.fr> wrote:
> I captured a full trace of this occurrence with
> echo *:* > $TRACING/set_event
> cat $TRACING/per_cpu/cpu$CPU/trace > trace.$CPU
...
> But there is absolutely NOTHING traced between 4606.628019 & 4606.811832.
I recommend using the function tracer:
# echo function > $TRACING/current_tracer
It should not affect your timings for pure-userspace code. This should
catch any unintentional kernel activity.
John
next prev parent reply other threads:[~2025-09-09 12:35 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-04 23:45 Large(ish) variance induced by SCHED_FIFO Marc Gonzalez
2025-09-05 8:25 ` Daniel Wagner
2025-09-05 13:23 ` Marc Gonzalez
2025-09-05 14:03 ` John Ogness
2025-09-05 15:34 ` Marc Gonzalez
2025-09-05 16:07 ` John Ogness
2025-09-05 17:40 ` Marc Gonzalez
2025-09-08 9:36 ` John Ogness
2025-09-08 15:42 ` Marc Gonzalez
2025-09-08 16:02 ` Daniel Wagner
2025-09-08 18:40 ` Marc Gonzalez
2025-09-09 11:08 ` Unexplained variance in run-time of trivial program Marc Gonzalez
2025-09-09 11:21 ` Daniel Wagner
2025-09-09 12:42 ` Marc Gonzalez
2025-09-09 14:23 ` Steven Rostedt
2025-09-09 12:34 ` John Ogness [this message]
2025-09-09 14:08 ` Marc Gonzalez
2025-09-09 18:33 ` Marc Gonzalez
[not found] ` <CAMjhiJjMOQN-nWd+KP4JBBNHf20M+J2fXAuTTvowXctJgvGOcQ@mail.gmail.com>
2025-09-09 20:30 ` Marc Gonzalez
2025-09-10 7:59 ` Daniel Wagner
2025-09-11 21:29 ` Marc Gonzalez
2025-09-11 22:15 ` Marc Gonzalez
2025-09-12 7:44 ` Daniel Wagner
2025-09-13 10:09 ` Marc Gonzalez
2025-09-15 16:30 ` Marc Gonzalez
2025-09-16 7:50 ` Ahmed S. Darwish
2025-09-25 11:38 ` Marc Gonzalez
2025-09-08 16:52 ` [EXT] Re: Large(ish) variance induced by SCHED_FIFO Rui Sousa
2025-09-08 17:03 ` Marc Gonzalez
[not found] ` <CAMjhiJiVDmnx+pgpvtAy=KarHexjsYs+T9tSkpGvppjqFdtmiw@mail.gmail.com>
2025-09-05 21:05 ` Marc Gonzalez
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