linux-kernel - Re: perf samples too long without perf running (?!?)

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Date:	Sat, 08 Mar 2014 08:51:18 +0100
From:	Mike Galbraith <umgwanakikbuti@...il.com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: perf samples too long without perf running (?!?)

On Fri, 2014-03-07 at 17:57 -0800, Andy Lutomirski wrote: 
> On recent (3.13) kernels, I'm frequently getting messages like:
> 
> perf samples too long (2503 > 2500), lowering
> kernel.perf_event_max_sample_rate to 50000
> 
> a few seconds to minutes after bootup.  As far as I know, I'm not
> using perf.  What's going on here?

14c63f17b1

I get those all the time too, just building kernels.

[  598.583918] perf samples too long (2539 > 2500), lowering kernel.perf_event_max_sample_rate to 50000

Darn nmi_watchdog is an expensive employee.  Scarier are the ones from
2ab00456ea when using perf.  Firing the dog makes it all batter.

-Mike

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