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From: Vince Weaver <vincent.weaver@maine.edu>
To: Vince Weaver <vincent.weaver@maine.edu>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Jiri Olsa <jolsa@redhat.com>,
	Stephane Eranian <eranian@google.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	mingo@elte.hu, Andi Kleen <ak@linux.intel.com>
Subject: Re: [RFC] perf/core: what is exclude_idle supposed to do
Date: Fri, 20 Apr 2018 12:51:12 -0400 (EDT)	[thread overview]
Message-ID: <alpine.DEB.2.21.1804201247050.28907@macbook-air> (raw)
In-Reply-To: <alpine.DEB.2.21.1804201015250.22578@macbook-air>

On Fri, 20 Apr 2018, Vince Weaver wrote:

> > AFAICT it works on Power and possibly ARM.
> 
> at least some ARMs are a bit more honest about it than x86
> 
> ivybridge:
> 	Performance counter stats for '/bin/ls':
> 	1,368,162      instructions
> 	1,368,162      instructions:I
> 
> pi2/ARM cortex-A7
> 	Performance counter stats for '/bin/ls':
> 	1,910,083      instructions
> 	<not supported>      instructions:I
> 
> I'd fire up my Power8 machine to see but not sure it's worth the hassle 
> and/or having to get out the ear protection.

I did power up the Power8 machine in the end:

power8:
	perf stat -e cycles,cycles:I sleep 5
	Performance counter stats for 'sleep 5':
        14,271,273      cycles
        14,271,273      cycles:I

???

But then if I try again on power8

	perf stat -a -e cycles,cycles:I sleep 5
	 Performance counter stats for 'system wide':
	1,238,772,322,327      cycles
 	1,238,674,771,713      cycles:I   

there is a difference.

But then on ivybridge

	perf stat -a -e cycles,cycles:I sleep 5
	Performance counter stats for 'system wide':
	589,598,104      cycles
	589,537,190      cycles:I

there is also a different in system wide mode.

So maybe exclude_idle does do something on x86?  Or am I completely 
misunderstanding what the flag is supposed to be indicating?

Vince

  reply	other threads:[~2018-04-20 16:51 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-16 22:04 Stephane Eranian
2018-04-17  6:20 ` Jiri Olsa
2018-04-18 15:10   ` Vince Weaver
2018-04-20  8:36     ` Peter Zijlstra
2018-04-20 14:18       ` Vince Weaver
2018-04-20 16:51         ` Vince Weaver [this message]
2018-04-20 18:19           ` Stephane Eranian
2018-04-17 13:40 ` Arnaldo Carvalho de Melo
2018-04-20  8:35 ` Peter Zijlstra

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