linux-kernel - Re: [PATCH 8/9] perf report: Add report.percent-limit config variable

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Message-ID: <51948C1B.20408@kernel.org>
Date:	Thu, 16 May 2013 10:34:51 +0300
From:	Pekka Enberg <penberg@...nel.org>
To:	Namhyung Kim <namhyung@...nel.org>
CC:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...nel.org>,
	Namhyung Kim <namhyung.kim@....com>,
	LKML <linux-kernel@...r.kernel.org>,
	Jiri Olsa <jolsa@...hat.com>, David Ahern <dsahern@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH 8/9] perf report: Add report.percent-limit config variable

On 05/15/2013 01:08 PM, Namhyung Kim wrote:
> Hi Pekka,
>
> On Tue, 14 May 2013 14:05:38 +0300, Pekka Enberg wrote:
>> On Tue, May 14, 2013 at 5:09 AM, Namhyung Kim <namhyung@...nel.org> wrote:
>>> From: Namhyung Kim <namhyung.kim@....com>
>>>
>>> Now an user can set a default value of --percent-limit option into the
>>> perfconfig file.
>>>
>>>    $ cat ~/.perfconfig
>>>    [report]
>>>    percent-limit = 0.1
>>>
>>> Cc: Andi Kleen <andi@...stfloor.org>
>>> Cc: Pekka Enberg <penberg@...nel.org>
>>> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
>>
>> I'm not totally convinced this is useful. The limit is about "what is
>> significant" and that depends on what you are trying to measure.
>> There's an (absolute) lower limit somewhere between 0.1 and 1.0 but I
>> think we can just pick a reasonable default and  let people use the
>> command line switch if they want to override it.
>
> If the limit depends on what is measured, what should be the reasonable
> default value?  I just don't know..
>
> I agree that we should pick a default but the config variable doesn't
> harm anything in this case too.  Some users might not agree with our
> default for their cases and want to use other value.
>
> But I'm not insist on it so strongly, I just gave another way.. ;)

I'd go for default value of 1.0 first and if people complain, drop it to 
0.1. But I guess it's safer to add your config option thingy just in case:

Acked-by: Pekka Enberg <penberg@...nel.org>

			Pekka
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