From: David Ahern <dsahern@gmail.com>
To: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Milian Wolff <mail@milianw.de>,
linux-perf-users <linux-perf-users@vger.kernel.org>,
Namhyung Kim <namhyung@gmail.com>, Ingo Molnar <mingo@kernel.org>,
Joseph Schuchart <joseph.schuchart@tu-dresden.de>
Subject: Re: Perf event for Wall-time based sampling?
Date: Fri, 19 Sep 2014 08:17:47 -0600 [thread overview]
Message-ID: <541C3B0B.3030706@gmail.com> (raw)
In-Reply-To: <20140918203625.GM2770@kernel.org>
On 9/18/14, 2:36 PM, Arnaldo Carvalho de Melo wrote:
> Ok, so you want to see what is the wait channel and unwind the stack
> from there? Is that the case? I.e. again, a sysrq-t equivalent?
>
>> Milian want is to grab samples every timer expiration even if process is not
>> running.
>
> What for? And by "grab samples" you want to know where it is waiting for
> something, together with its callchain?
>
>> Any limitations that would prevent doing this with a sw event? e.g, mimic
>> task-clock just don't disable the timer when the task is scheduled out.
>
> I'm just trying to figure out if what people want is a complete
> backtrace of all threads in a process, no matter what they are doing, at
> some given time, i.e. at "sysrq-t" time, is that the case?
This has been discussed before:
http://thread.gmane.org/gmane.linux.kernel/1307306
Example on the perf wiki:
https://perf.wiki.kernel.org/index.php/Tutorial#Profiling_sleep_times
David
next prev parent reply other threads:[~2014-09-19 14:17 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-18 12:32 Perf event for Wall-time based sampling? Milian Wolff
2014-09-18 13:23 ` Arnaldo Carvalho de Melo
2014-09-18 13:41 ` Milian Wolff
2014-09-18 14:51 ` Arnaldo Carvalho de Melo
2014-09-18 15:26 ` Milian Wolff
2014-09-18 15:57 ` Arnaldo Carvalho de Melo
2014-09-18 16:37 ` Milian Wolff
2014-09-18 19:17 ` Arnaldo Carvalho de Melo
2014-09-18 19:31 ` Arnaldo Carvalho de Melo
2014-09-18 20:17 ` David Ahern
2014-09-18 20:36 ` Arnaldo Carvalho de Melo
2014-09-18 20:39 ` David Ahern
2014-09-19 8:11 ` Milian Wolff
2014-09-19 9:08 ` Milian Wolff
2014-09-19 14:47 ` Arnaldo Carvalho de Melo
2014-09-19 15:04 ` David Ahern
2014-09-19 15:05 ` Milian Wolff
2014-09-19 14:17 ` David Ahern [this message]
2014-09-19 14:39 ` Milian Wolff
2014-09-19 14:55 ` David Ahern
2014-09-19 5:59 ` Namhyung Kim
2014-09-19 14:33 ` Arnaldo Carvalho de Melo
2014-09-19 14:53 ` Milian Wolff
2014-09-19 15:50 ` Namhyung Kim
2014-09-22 7:56 ` Namhyung Kim
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