linux-kernel - Re: [PATCH 2/2] perf stat: Remove nmi watchdog check code again

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Message-ID: <20160609172010.GB1704@kernel.org>
Date:	Thu, 9 Jun 2016 14:20:10 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	peterz@...radead.org, x86@...nel.org, linux-kernel@...r.kernel.org,
	jolsa@...nel.org, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 2/2] perf stat: Remove nmi watchdog check code again

Em Thu, Jun 09, 2016 at 08:17:16AM -0700, Andi Kleen escreveu:
> On Thu, Jun 09, 2016 at 10:42:08AM -0300, Arnaldo Carvalho de Melo wrote:
> > Em Thu, Jun 09, 2016 at 06:14:39AM -0700, Andi Kleen escreveu:
> > > Now that the NMI watchdog runs with reference cycles, and does not

> > Now as in when? We should at least warn the user that the kernel used is
> > one where the NMI watchdog will not get in the way of topdown. Is there
> > a programmatic way to discover that?
 
> If the other patch gets merged at the same time as the TopDown patches
> it's only a few days in tip which don't support it, no released kernel.
> So no need to check for this case.

Ok, I see, since on older kernels it will fail before that point, when
not finding the topdown counters, no problem, super small window, thanks
for clarifying.

- Arnaldo