From: Mathieu Desnoyers <compudj@krystal.dyndns.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: prasad@linux.vnet.ibm.com, jan.kiszka@web.de,
Gian Lorenzo Meocci <glmeocci@gmail.com>,
ltt-dev@lists.casi.polymtl.ca, linux-kernel@vger.kernel.org,
mbligh@google.com
Subject: Re: [ltt-dev] trace a futex
Date: Fri, 5 Dec 2008 07:28:22 -0500 [thread overview]
Message-ID: <20081205122822.GA25816@Krystal> (raw)
In-Reply-To: <1228380784.5092.18.camel@twins>
* Peter Zijlstra (peterz@infradead.org) wrote:
>
> FWIW, the ftrace infrastructure has on many an occasion (even before it
> was called ftrace and specific to -rt) helped in debugging and fixing
> futex races.
>
Hrm, I'm not sure futex races is the key aspect of interest here.
Knowing which amount of pthread mutex lock calls ends up calling the
scheduler looks a bit more like the topic brought by this particular
use-case. Therefore, correlating the information from the nptl with the
kernel information would be useful.
Is lockdep called when a futex is taken ? Should we add instrumentation
(tracepoints) to futex.c ? If yes, was there specific instrumentation
you used with ftrace that should be added ?
Mathieu
--
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
next prev parent reply other threads:[~2008-12-05 12:33 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <8d94e9280812021142j2eb5ca72td730410e97ccd9a1@mail.gmail.com>
[not found] ` <20081202195015.GA25792@Krystal>
[not found] ` <8d94e9280812021215m6a63d6c2l4e64acd26274953d@mail.gmail.com>
[not found] ` <20081202215519.GA734@Krystal>
[not found] ` <4935B25F.7010701@web.de>
2008-12-03 5:26 ` [ltt-dev] trace a futex Mathieu Desnoyers
2008-12-03 18:01 ` K.Prasad
2008-12-04 8:53 ` Peter Zijlstra
2008-12-05 12:28 ` Mathieu Desnoyers [this message]
2008-12-05 15:58 ` Peter Zijlstra
2008-12-05 16:01 ` Peter Zijlstra
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