From: Stephane Eranian <eranian@google.com>
To: Frederic Weisbecker <fweisbec@gmail.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 16:10:24 +0100 [thread overview]
Message-ID: <CABPqkBT7bTZ83j2yjWoQO-HQhg+=WsqD0sE_D+_Vi_HTZKKCxA@mail.gmail.com> (raw)
In-Reply-To: <20120208150715.GB25473@somewhere.redhat.com>
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.
> 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.
next prev parent reply other threads:[~2012-02-08 15:10 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 [this message]
2012-02-08 15:22 ` Frederic Weisbecker
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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