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Date: Wed, 5 Nov 2008 22:16:59 -0800
Message-ID: <b040c32a0811052216i4594a094gdcee3ae280cddec7@mail.gmail.com>
Subject: Re: [patch] sched: fix single-depth wchan output
From: Ken Chen <kenchen@google.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Steven Rostedt <rostedt@goodmis.org>
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On Wed, Nov 5, 2008 at 10:11 PM, Ingo Molnar <mingo@elte.hu> wrote:
> hm, this adds overhead - and the thing is that WCHAN is rather
> uninformative to begin with (because it's a single dimension), so we
> should phase it out, not expand it.
>
> How about adding a /proc/<PID>/stacktrace file that gives us the stack
> trace of any task in the system? That would be useful for a number of
> other purposes as well, and about 100 times more useful than wchan.
> (often it would be more useful than sysrq-t dumps)

Sure, my main motivation is to remove frame pointer generation. x86_64
unconditionally adds fp for kernel/sched.c right now.  I'm all for
phasing out wchan if people don't think there is value in it.

- Ken
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