linux-kernel - Re: [BUG] perf: perf sched warning possibly due to clock granularity on AMD

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Message-ID: <20120206171721.GB6367@infradead.org>
Date:	Mon, 6 Feb 2012 15:17:21 -0200
From:	Arnaldo Carvalho de Melo <acme@...hat.com>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org, mingo@...e.hu,
	robert.richter@....com, eric.dumazet@...il.com,
	Borislav Petkov <bp@...64.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [BUG] perf: perf sched warning possibly due to clock
	granularity on AMD

Em Mon, Feb 06, 2012 at 03:31:00PM +0100, Stephane Eranian escreveu:
> On Mon, Feb 6, 2012 at 3:26 PM, Peter Zijlstra <peterz@...radead.org> wrote:
> > On Mon, 2012-02-06 at 14:25 +0100, Stephane Eranian wrote:
> >> In summary, two issues:
> >>   - Why is sched_clock_stable not set or even tested on recent AMD systems?
> >
> > I'll leave that for Robert to answer, also added Boris to the CC, him
> > know AMD bits too.
> >
> Ok, good.
> 
> >>   - perf should not rely on fine granularity timestamps in the re-ordering code
> >
> > Uhm, what else is there?

> I understand your point. I don't quite understand what the code is
> supposed to do for odered
> samples. I'd like Arnaldo to explain this warning first.

That code was written by Frédéric and IIRC also Thomas, its something I
plan to rework somehow in the future, but for now I'll let them chime
in... Frédéric?

- Arnaldo
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