linux-kernel - Re: perf: h/w counters not counted and no error/info reported to user

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Date:	Fri, 27 May 2011 10:36:07 -0600
From:	David Ahern <dsahern@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: perf: h/w counters not counted and no error/info reported to
 user



On 05/27/2011 09:04 AM, David Ahern wrote:
> How is the <not counted> supposed to be interpreted?
> 
> Also, back to the 'perf stat -- sleep 1' example: If I run it with
> individual -e <event> args I get values -- up to 3. Sure sleep is a
> simple program, but some counter value comes out. What's magical about 3?

Ok, I got it now. On some occasions for simple programs -- like sleep 1
-- the counter reads show:

cycles: 0 1066485 0

While the counter value is non-0, the time enabled and running values
are 0 and those latter two are used by stat to say "not-counted".

Unsupported events have 0's across the board. I'm working on a patch to
change <not counted> to <not supported> for events marked as unsupported.

David
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