From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1755434Ab2BHPWJ (ORCPT <rfc822;w@1wt.eu>);
	Wed, 8 Feb 2012 10:22:09 -0500
Received: from mail-yx0-f174.google.com ([209.85.213.174]:62502 "EHLO
	mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1754178Ab2BHPWI (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Wed, 8 Feb 2012 10:22:08 -0500
Date: Wed, 8 Feb 2012 16:22:03 +0100
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
Message-ID: <20120208152200.GC25473@somewhere.redhat.com>
References: <20120206132546.GA30854@quad>
 <20120208150715.GB25473@somewhere.redhat.com>
 <CABPqkBT7bTZ83j2yjWoQO-HQhg+=WsqD0sE_D+_Vi_HTZKKCxA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <CABPqkBT7bTZ83j2yjWoQO-HQhg+=WsqD0sE_D+_Vi_HTZKKCxA@mail.gmail.com>
User-Agent: Mutt/1.5.21 (2010-09-15)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

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!