linux-kernel - Re: Strange behavior of perf top with PEBS

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Date:	Tue, 26 Jul 2016 14:30:46 +0300
From:	Nikolay Borisov <kernel@...p.com>
To:	Jiri Olsa <jolsa@...hat.com>, Nikolay Borisov <kernel@...p.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	"Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>,
	andi@...stfloor.org
Subject: Re: Strange behavior of perf top with PEBS



On 07/20/2016 05:38 PM, Jiri Olsa wrote:
> On Wed, Jul 20, 2016 at 04:34:17PM +0200, Jiri Olsa wrote:
>> 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
> 
> oops, too soon ;) we have:
> 
> perf/x86/intel: Fix Core2,Atom,NHM,WSM cycles:pp events
> commit 517e6341fa123ec3a2f9ea78ad547be910529881
> Author: Peter Zijlstra <peterz@...radead.org>
> Date:   Sat Apr 11 12:16:22 2015 +0200
> 
> 
> so i guess it should work.. checking ;-)

Any update on that?

> 
> jirka
>