Re: libc/1427: gprof does not profile threads <synopsis of the problem

[Dan Kegel <dkegel@ixiacom.com>]

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