linux-kernel - Re: [PATCH] perf tool: don't print bogus data on -e instructions

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Message-ID: <20131001084831.GG21793@gmail.com>
Date:	Tue, 1 Oct 2013 10:48:31 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Ramkumar Ramachandra <artagnon@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>
Subject: Re: [PATCH] perf tool: don't print bogus data on -e instructions


* Ramkumar Ramachandra <artagnon@...il.com> wrote:

> When only the instructions event is requested:
> 
> $ perf stat -e instructions git s
> M  builtin-stat.c
> 
>  Performance counter stats for 'git s':
> 
>        917,453,420 instructions              #    0.00  insns per cycle
> 
>        0.213002926 seconds time elapsed
> 
> The 0.00 insns per cycle comment in the output is totally bogus and
> misleading. It happens because update_shadow_stats() doesn't touch
> runtime_cycles_stats when only the instructions event is requested. So,
> omit printing the bogus data altogether.
> 
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> Cc: Paul Mackerras <paulus@...ba.org>
> Cc: Arnaldo Carvalho de Melo <acme@...stprotocols.net>
> Signed-off-by: Ramkumar Ramachandra <artagnon@...il.com>

Acked-by: Ingo Molnar <mingo@...nel.org>

Thanks,

	Ingo
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