Re: "perf: interrupt took too long" messages even with perf_cpu_time_max_percent==0

From	Markus Trippelsdorf <markus@trippelsdorf.de>
Newsgroups	linux.kernel
Subject	Re: "perf: interrupt took too long" messages even with perf_cpu_time_max_percent==0
Date	2016-04-13 12:10 +0200
Message-ID	<rnpUd-86v-7@gated-at.bofh.it> (permalink)
References	<rjqcb-1I3-39@gated-at.bofh.it> <rjrBf-2Rm-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 2016.04.02 at 13:00 +0200, Peter Zijlstra wrote:
> On Sat, Apr 02, 2016 at 11:32:39AM +0200, Markus Trippelsdorf wrote:
> > Current git kernel sometimes shows:
> > 
> >  perf: interrupt took too long (71 > 52), lowering kernel.perf_event_max_sample_rate to 300
> >  perf: interrupt took too long (103 > 88), lowering kernel.perf_event_max_sample_rate to 300
> >  perf: interrupt took too long (130 > 128), lowering kernel.perf_event_max_sample_rate to 300
> >  perf: interrupt took too long (175 > 162), lowering kernel.perf_event_max_sample_rate to 300
> >  perf: interrupt took too long (219 > 218), lowering kernel.perf_event_max_sample_rate to 300
> > ...
> > 
> > when running e.g. "perf top" even when  
> > /proc/sys/kernel/perf_cpu_time_max_percent is set to 0.
> 
> 
> Ah, was 0 also meant to disable it?
> 
> Does the below help?

Yes, it obviously fixes the issue.

-- 
Markus

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Re: "perf: interrupt took too long" messages even with  perf_cpu_time_max_percent==0 Markus Trippelsdorf <markus@trippelsdorf.de> - 2016-04-13 12:10 +0200

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