linux-kernel - Re: [PATCH 1/2 -tip] perf_counter: Add generalized hardware vectored co-processor support for AMD and Intel Corei7/Nehalem

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Date:	Sat, 4 Jul 2009 11:49:21 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Jaswinder Singh Rajput <jaswinder@...nel.org>
Cc:	Arjan van de Ven <arjan@...radead.org>,
	Paul Mackerras <paulus@...ba.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Anton Blanchard <anton@...ba.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	x86 maintainers <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [PATCH 1/2 -tip] perf_counter: Add generalized hardware
	vectored co-processor support for AMD and Intel Corei7/Nehalem


* Jaswinder Singh Rajput <jaswinder@...nel.org> wrote:

> On Fri, 2009-07-03 at 12:29 +0200, Ingo Molnar wrote:
> > * Jaswinder Singh Rajput <jaswinder@...nel.org> wrote:
> > 
> > >  Performance counter stats for '/usr/bin/rhythmbox /home/jaswinder/Music/singhiskinng.mp3':
> > > 
> > >        17552264  vec-adds                  (scaled from 66.28%)
> > >        19715258  vec-muls                  (scaled from 66.63%)
> > >        15862733  vec-divs                  (scaled from 66.82%)
> > >     23735187095  vec-idle-cycles           (scaled from 66.89%)
> > >        11353159  vec-stall-cycles          (scaled from 66.90%)
> > >        36628571  vec-ops                   (scaled from 66.48%)
> > 
> > Is stall-cycles equivalent to busy-cycles? 
> 
> 
> hmm, normally we can use these terms interchangeably. But they can 
> be different some times.
> 
> busy means it is already executing some instructions so it will 
> not take another instruction.
> 
> stall can be busy(executing) or non-executing may be it is waiting 
> for some operands due to cache miss.
> 
> 
> > I.e. do we have this 
> > general relationship to the cycle event:
> > 
> > 	cycles = vec-stall-cycles + vec-idle-cycles
> > 
> > ?
> 
> This patch is already big enough, having 206 lines. Do you want 
> everything in this patch ;-)

The question i asked is whether the above relationship is true. You 
can test this by displaying the 'cycles' metric too in your test, 
alongside vec-stall-cycles and vec-idle-cycles. Do the numbers add 
up?

	Ingo
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