linux-kernel - Re: [BUG] perf stat: explicit grouping yields unexpected results

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Message-ID: <CABPqkBShEo0hdJuKaHQZPtQ+qO1kayup70auGxt6jYxk+MthLA@mail.gmail.com>
Date:	Fri, 15 Nov 2013 12:58:29 +0100
From:	Stephane Eranian <eranian@...gle.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Jiri Olsa <jolsa@...hat.com>, "mingo@...e.hu" <mingo@...e.hu>,
	David Ahern <dsahern@...il.com>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Namhyung Kim <namhyung.kim@....com>
Subject: Re: [BUG] perf stat: explicit grouping yields unexpected results

On Fri, Nov 15, 2013 at 12:52 PM, Peter Zijlstra <peterz@...radead.org> wrote:
> On Fri, Nov 15, 2013 at 11:34:05AM +0100, Ingo Molnar wrote:
>> That brings up an interesting question: what is better for users, if
>> we schedule as many as we can and say 'not supported' to the rest
>> (current behavior), or if we fail the whole group?
>>
>> I'd say that the default behavior should be what Jiri implemented: get
>> the most out of the situation and inform. But you are right in that
>> 'forcing' all elements of a group to be valid should be possible as
>> well - if a special perf stat option or event format is used.
>
> So I don't agree, but if you want to keep this IMO weird behaviour at
> least WARN about it in big blinking neon letters that the user isn't
> getting what he asked for.

Agreed.
When I tested this, I already knew what to expect, that's why I was
surprised not to get any warning or error messages.
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