linux-kernel - Re: [tip:perf/core] perf/x86/intel/P4: Robistify P4 PMU types

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Message-ID: <20130427163330.GS13008@moon>
Date:	Sat, 27 Apr 2013 20:33:30 +0400
From:	Cyrill Gorcunov <gorcunov@...nvz.org>
To:	Borislav Petkov <bp@...en8.de>
Cc:	mingo@...nel.org, hpa@...or.com, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org, a.p.zijlstra@...llo.nl,
	tytso@....edu, davem@...emloft.net, fweisbec@...il.com,
	oleg@...hat.com, tglx@...utronix.de,
	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:perf/core] perf/x86/intel/P4: Robistify P4 PMU types

On Sat, Apr 27, 2013 at 06:14:07PM +0200, Borislav Petkov wrote:
...

Thanks a LOT, Borislav!

> The other trivial test passes too, although branch-misses doesn't get
> counted:
> 
> ./perf stat sleep 1
> 
>  Performance counter stats for 'sleep 1':
> 
>           1.433368 task-clock                #    0.001 CPUs utilized          
>                  1 context-switches          #    0.698 K/sec                  
>                  0 cpu-migrations            #    0.000 K/sec                  
>                147 page-faults               #    0.103 M/sec                  
>             78,446 cycles                    #    0.055 GHz                    
>                  0 stalled-cycles-frontend   #    0.00% frontend cycles idle   
>                  0 stalled-cycles-backend    #    0.00% backend  cycles idle    [27.37%]
>          1,268,044 instructions              #   16.16  insns per cycle         [27.37%]
>            223,742 branches                  #  156.095 M/sec                   [27.37%]
>      <not counted> branch-misses
> 
>        1.002191045 seconds time elapsed

It's known effect. instructions retired and branch-misses can't
run simultaneously since they both use same escr msr register
(if I recall correctly, out of repo at moment).

> However, if I do this, it works:
> 
> ./perf stat -e branch-misses sleep 1
> 
>  Performance counter stats for 'sleep 1':
> 
>              8,583 branch-misses
> 
>        1.001992384 seconds time elapsed

Thanks!
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