linux-kernel - Re: [PATCH] perf stat: Don't print bogus data when one event is requested

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Message-ID: <20140409130934.GC2556@krava.brq.redhat.com>
Date:	Wed, 9 Apr 2014 15:09:34 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	Ramkumar Ramachandra <artagnon@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH] perf stat: Don't print bogus data when one event is
 requested

On Thu, Mar 27, 2014 at 06:20:59PM -0400, Ramkumar Ramachandra wrote:
> When only the stalled-cycles-frontend event is requested:
> 
>   $ perf stat -e stalled-cycles-frontend -- git s
>   ## acme...ram/acme
> 
>    Performance counter stats for 'git s':
> 
>          326,947,423      stalled-cycles-frontend   #    0.00% frontend cycles idle
> 
>          0.363599976 seconds time elapsed
> 
> The 0.00% frontend cycles idle comment in the output is totally bogus
> and misleading. Omit printing it here, as well as in the
> stalled-cycles-backend case.

hi,
I agree with the change, but the reason for 0% is not only that
'one' event was stated, but that 'cycles' event is missing in
measurement.

Please change your changelog accordingly, the change itself
looks ok.

thanks,
jirka
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