From: Andrew Vagin <avagin@parallels.com>
To: Arun Sharma <asharma@fb.com>
Cc: Andrew Vagin <avagin@openvz.org>,
linux-kernel@vger.kernel.org,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Paul Mackerras <paulus@samba.org>, Ingo Molnar <mingo@elte.hu>,
Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
devel@openvz.org
Subject: Re: [PATCH 3/4] perf: teach perf inject to merge sched_stat_* and sched_switch events
Date: Mon, 07 Nov 2011 16:56:06 +0400 [thread overview]
Message-ID: <4EB7D566.40900@parallels.com> (raw)
In-Reply-To: <4EB32D1B.8060305@fb.com>
Hi Arun,
On 11/04/2011 04:08 AM, Arun Sharma wrote:
> On 11/2/11 3:59 PM, Andrew Vagin wrote:
>
>> + event_sw = (union perf_event *)&ent->header;
>
> This causes problems with -Wstrict-aliasing=3.
I didn't see any warning, but I reworked this part a bit.
>
> I noticed that the suggested cmdline is:
>
> perf script record sched-stat -- -e sched:sched_stat_sleep
>
> I'd much prefer something along the lines of:
>
> perf script record sched-stat -e <events> -- sleep 1
>
> Also, the perf inject command is a bit unforgiving when the user makes
> some mistakes (eg: didn't specify -e sched:sched_stat_sleep). The
> failure mode is hard to understand (perf report -i perf.data.d fails
> with "no samples").
I see the problem. It's not in "perf inject". Look at new version I
improved "perf script sched_stat". Now it may be executed for specific
command and it reports an error if you forgot to set a sched_stat_* event.
> Could not find sched_switch for pid 16179
>
> I think this is the same issue you referenced in "Known issues".
Actually It isn't. Now I print this message as debug information.
>
> Although I'm able to get some profiling info out of perf.data.d, the
> process I really wanted to trace got zero samples.
It's strange. Can you check new versions and describe the experiment if
it will be reproduces.
>
> -Arun
>
next prev parent reply other threads:[~2011-11-07 12:56 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-02 22:59 [PATCH 0/4] Profiling sleep times Andrew Vagin
2011-11-02 22:59 ` [PATCH 1/4] perf: use event_name() to get an event name Andrew Vagin
2011-11-02 22:59 ` [PATCH 2/4] perf: teach "perf inject" to work with files Andrew Vagin
2011-11-02 22:59 ` [PATCH 3/4] perf: teach perf inject to merge sched_stat_* and sched_switch events Andrew Vagin
2011-11-04 0:08 ` Arun Sharma
2011-11-07 12:56 ` Andrew Vagin [this message]
2011-11-02 22:59 ` [PATCH 4/4] perf: add scripts for profiling sleep times Andrew Vagin
2011-11-03 1:07 ` Arun Sharma
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