Re: Strange behavior of perf top with PEBS

From	Jiri Olsa <jolsa@redhat.com>
Newsgroups	linux.kernel
Subject	Re: Strange behavior of perf top with PEBS
Date	2016-07-20 16:40 +0200
Message-ID	<rX0Pf-2Cz-15@gated-at.bofh.it> (permalink)
References	<rWZJv-1YB-21@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Wed, Jul 20, 2016 at 04:28:34PM +0300, Nikolay Borisov wrote:
> Hello,
> 
> Running perf version 4.4.14.g0cb188d (no modification to the PMU/perf
> code) I observed that "perf top" counts no cycles and produces no
> output. After a bit of head scratching and testing I figured that
> running "perf top -e cycles" actually works whereas the default option
> is equivalent to running "perf top -e cycles:p". So the latter version
> seems to not work on my machine.

hum, I think Core2 has PEBs valid only for instructions not cycles..

I'll check why perf top forcing the precise for cycles
I thought we had that automated already

jirka

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Strange behavior of perf top with PEBS Nikolay Borisov <kernel@kyup.com> - 2016-07-20 15:30 +0200
  Re: Strange behavior of perf top with PEBS Nikolay Borisov <kernel@kyup.com> - 2016-07-20 16:40 +0200
  Re: Strange behavior of perf top with PEBS Jiri Olsa <jolsa@redhat.com> - 2016-07-20 16:40 +0200
  Re: Strange behavior of perf top with PEBS Jiri Olsa <jolsa@redhat.com> - 2016-07-20 16:40 +0200

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