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From: Frederic Weisbecker <fweisbec@gmail.com>
To: Stephane Eranian <eranian@google.com>
Cc: linux-kernel@vger.kernel.org, acme@redhat.com,
	peterz@infradead.org, mingo@elte.hu, robert.richter@amd.com,
	eric.dumazet@gmail.com
Subject: Re: [BUG] perf: perf sched warning possibly due to clock granularity on AMD
Date: Wed, 8 Feb 2012 16:22:03 +0100	[thread overview]
Message-ID: <20120208152200.GC25473@somewhere.redhat.com> (raw)
In-Reply-To: <CABPqkBT7bTZ83j2yjWoQO-HQhg+=WsqD0sE_D+_Vi_HTZKKCxA@mail.gmail.com>

On Wed, Feb 08, 2012 at 04:10:24PM +0100, Stephane Eranian wrote:
> On Wed, Feb 8, 2012 at 4:07 PM, Frederic Weisbecker <fweisbec@gmail.com> wrote:
> > On Mon, Feb 06, 2012 at 02:25:46PM +0100, Stephane Eranian wrote:
> >> Hi,
> >>
> >> I am running 3.3.30-rc2 on an AMD Bulldozer system in 64-bit mode.
> >> I was testing perf sched and I ran into an issue. That issue seems
> >> to exist only on AMD and not on Intel systems. It is not PMU related
> >> because I am doing tracing.
> >>
> >> I am running a simple ping pong test to stress the context switch
> >> code. Two processes exchanging a byte through a pipe (program provided
> >> below).
> >>
> >> Then, I capture a trace using perf sched, and I run sched lat, but
> >> on certain runs, I get:
> >>
> >>    $ perf sched rec pong 2
> >>    $ perf sched lat
> >>      Warning: Timestamp below last timeslice flush
> >>      Warning: Timestamp below last timeslice flush
> >>      Warning: Timestamp below last timeslice flush
> >>      Warning: Timestamp below last timeslice flush
> >>      Warning: Timestamp below last timeslice flush
> >>      Warning: Timestamp below last timeslice flush
> >>      Warning: Timestamp below last timeslice flush
> >>      Warning: Timestamp below last timeslice flush
> >>      Warning: TimesFound 4934 unknown events!
> >>      Is this an older tool processing a perf.data file generated by a more recent tool?
> >
> > I've tried to reproduce this on an AMD phenom but haven't got any such
> > warning.
> >
> It does not happen at each run.

Yeah I tried 5 times but wasn't lucky.

> 
> > Is there any chance you could "perf archive" your data and upload it somewhere
> > I can fetch it from?
> >
> I can send you the perf.data in a private Email.

Thanks!

  reply	other threads:[~2012-02-08 15:22 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-06 13:25 [BUG] perf: perf sched warning possibly due to clock granularity on AMD Stephane Eranian
2012-02-06 14:26 ` Peter Zijlstra
2012-02-06 14:31   ` Stephane Eranian
2012-02-06 17:17     ` Arnaldo Carvalho de Melo
2012-02-06 15:34   ` Borislav Petkov
2012-02-06 16:37     ` Peter Zijlstra
2012-02-06 16:46       ` Borislav Petkov
2012-02-06 16:54         ` Peter Zijlstra
2012-02-06 20:27           ` Borislav Petkov
2012-02-06 20:31             ` Peter Zijlstra
2012-02-06 20:37               ` Borislav Petkov
2012-02-06 21:19                 ` Venki Pallipadi
2012-02-07  7:51                   ` Peter Zijlstra
2012-02-07  8:32                   ` Ingo Molnar
2012-02-07  9:06                     ` Borislav Petkov
2012-02-07  9:50                       ` Ingo Molnar
2012-02-07 12:08                         ` [PATCH] x86, AMD: Set sched_clock_stable Borislav Petkov
2012-02-15 15:30                           ` Peter Zijlstra
2012-02-07 19:43 ` [tip:perf/core] x86/sched/perf/AMD: " tip-bot for Borislav Petkov
2012-02-08 15:07 ` [BUG] perf: perf sched warning possibly due to clock granularity on AMD Frederic Weisbecker
2012-02-08 15:10   ` Stephane Eranian
2012-02-08 15:22     ` Frederic Weisbecker [this message]
2012-02-08 15:23       ` Stephane Eranian
2012-02-18 16:50 ` [PATCH] perf tools: Fix ordering with unstable tsc Frederic Weisbecker
2012-02-22 15:35   ` Stephane Eranian
2012-02-22 15:39     ` David Ahern
2012-03-05 18:43   ` Frederic Weisbecker
2012-03-14 19:55   ` Arnaldo Carvalho de Melo
2012-03-14 20:07     ` David Ahern
2012-03-22  0:10     ` Frederic Weisbecker
2012-03-22 15:28       ` Arnaldo Carvalho de Melo

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