linux-kernel - Re: [BUG] perf report: different reports when run on terminal as opposed to script

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Date:	Wed, 31 Oct 2012 16:12:27 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Dhaval Giani <dhaval.giani@...il.com>
Cc:	Arnaldo de Melo <acme@...radead.org>, mingo@...nel.org,
	Peter Zijlstra <peterz@...radead.org>,
	akshay kumar <iit.akshay@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [BUG] perf report: different reports when run on terminal as opposed to script

On Tue, 30 Oct 2012 08:05:45 -0400, Dhaval Giani wrote:
> On Tue, Oct 30, 2012 at 3:42 AM, Namhyung Kim <namhyung@...nel.org> wrote:
>> Hi Dhaval,
>>
>> On Mon, 29 Oct 2012 12:45:53 -0400, Dhaval Giani wrote:
>>> On Mon, Oct 29, 2012 at 12:01 PM, Dhaval Giani <dhaval.giani@...il.com> wrote:
>>>> Hi,
>>>>
>>>> As part of a class assignment I have to collect some performance
>>>> statistics. In order to do so I run
>>>>
>>>> perf record -g <the program I have to profile>
>>>>
>>>> And in another window, I start 200 threads of the load generator
>>>> (which is not recorded by perf)
>>>>
>>>> This generates me statistics that I expect to see, and I am happy. As
>>>> this is academia and a class assignment, I need to collect information
>>>> and analyze it across different setups. Which of course meant I script
>>>> this whole thing, which basically is
>>>>
>>>> for i in all possibilities
>>>> do
>>>> perf record -g <the program I have to profile> &
>>>> WAITPID=$!
>>>> for j in NR_THREADS
>>>> do
>>>> <start load generator> &
>>>> KILLPID=$!
>>>> done
>>>> wait $PID
>>
>> You meant $WAITPID, right?
>>
>
> yes. grrr. I changed the name here to WAITPID for it to be clear and
> that was a fail. (I blame the cold)
>
>>
>>>> kill $KILLPID
>>
>> Doesn't it kill the last load generator only?
>>
>>
>
> Well, this was a bug in me typing the pseudo code. the actual script
> does "$KILLPID $!"

Okay, so I suspect that it might be affected by the autogroup scheduling
feature since you said running load generators in another window - I
guess it's a terminal.  How about running them with setsid?

Thanks,
Namhyung

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