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Date: Wed, 13 Mar 2002 17:08:50 -0800
From: Dan Kegel <dkegel@ixiacom.com>
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To: Alan Cox <alan@lxorguk.ukuu.org.uk>
CC: Ulrich Drepper <drepper@redhat.com>, darkeye@tyrell.hu, libc-gnats@gnu.org,
        gnats-admin@cygnus.com, sam@zoy.org,
        Xavier Leroy <Xavier.Leroy@inria.fr>, linux-kernel@vger.kernel.org,
        babt@us.ibm.com
Subject: Re: libc/1427: gprof does not profile threads <synopsis of the problem
In-Reply-To: <E16lK2q-000811-00@the-village.bc.nu>
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Alan Cox wrote:
> 
> > Here are a few alternate ideas off the top of my head:
> >
> > * Rip out Linuxthreads, replace it with NGPT, and
> > start fixing from there?  (Or does NGPT already fix this?)
> >
> > * Rewrite Linux's setitimer(ITIMER_PROF,...) to set up an
> > interval timer for all threads of the thread group.
> >
> > * Implement the profil() system call from Solaris
> > ( http://ua1vm.ua.edu/cgi-bin/man-cgi?profil+2 )
> >
> > What's your favorite idea for getting profiling of
> > multithreaded programs working on Linux?
> 
> Kernel support is not needed  for this, do it in user space. Or prove it
> has to be in kernel space

I'm all in favor of a userspace fix.  I suggested a patch
to glibc to fix this.  Ulrich rejected it; I'm trying
to coax out of him how he thinks profiling of multithreaded
programs on Linux should be fixed.

I hope we can all at least agree that
  cc foo.c -pg -pthread
  ./a.out
  gprof a.out
should work in Linux without any workarounds on the part of the programmer...

- Dan


- Dan
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