From mboxrd@z Thu Jan  1 00:00:00 1970
From: Pavel Machek <pavel@ucw.cz>
Subject: Re: System crash with perf_fuzzer (kernel: 5.0.0-rc3)
Date: Thu, 7 Mar 2019 00:09:53 +0100
Message-ID: <20190306230953.GC7915@amd>
References: <7c7ec3d9-9af6-8a1d-515d-64dcf8e89b78@linux.ibm.com>
 <20190125160056.GG6118@tassilo.jf.intel.com>
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Sender: linux-kernel-owner@vger.kernel.org
To: Andi Kleen <ak@linux.intel.com>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>, lkml <linux-kernel@vger.kernel.org>, Jiri Olsa <jolsa@redhat.com>, Peter Zijlstra <peterz@infradead.org>, linux-perf-users@vger.kernel.org, Arnaldo Carvalho de Melo <acme@kernel.org>, eranian@google.com, vincent.weaver@maine.edu, "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
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On Fri 2019-01-25 08:00:56, Andi Kleen wrote:
> > [Fri Jan 25 10:28:53 2019] perf: interrupt took too long (2501 > 2500),=
 lowering kernel.perf_event_max_sample_rate to 79750
> > [Fri Jan 25 10:29:08 2019] perf: interrupt took too long (3136 > 3126),=
 lowering kernel.perf_event_max_sample_rate to 63750
> > [Fri Jan 25 10:29:11 2019] perf: interrupt took too long (4140 > 3920),=
 lowering kernel.perf_event_max_sample_rate to 48250
> > [Fri Jan 25 10:29:11 2019] perf: interrupt took too long (5231 > 5175),=
 lowering kernel.perf_event_max_sample_rate to 38000
> > [Fri Jan 25 10:29:11 2019] perf: interrupt took too long (6736 > 6538),=
 lowering kernel.perf_event_max_sample_rate to 29500
>=20
> These are fairly normal.

Unfortunately, they are. Could we set up our defaults so that they
don't normally happen?

pavel@amd:~/g/unicsy_demo$ dmesg | grep "took too"
[  761.507893] perf: interrupt took too long (2516 > 2500), lowering
kernel.perf_event_max_sample_rate to 79250
[ 4736.674595] perf: interrupt took too long (3209 > 3145), lowering
kernel.perf_event_max_sample_rate to 62250
pavel@amd:~/g/unicsy_demo$


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