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Subject: Re: [OMPI devel] Setting AUTOMAKE_JOBS
From: Ralf Wildenhues (Ralf.Wildenhues_at_[hidden])
Date: 2010-09-24 00:26:05


Hello Ralph,

wow, that's not good to hear. I knew the perl ithreads implementation
wasn't all that efficient, but causing a deadlock sounds like you have
more trouble than just perl; at least I hope so. For reference, can
you send 'perl -V' output (if you like, to the bug-automake at gnu.org
list).

Thanks,
Ralf

* Ralph Castain wrote on Fri, Sep 24, 2010 at 03:12:16AM CEST:
> I found one major negative to this change - it assumes that my build is
> being done in exclusion of anything else on my computer. Unfortunately, this
> is never true.
>
> So my laptop hemorrhaged itself into frozen silence, overheated to the point
> of being burning hot, and had to have its battery yanked to stop the runaway
> behavior. Not a really good thing.
>
> I would suggest you default this "heuristic" out, and let someone set it to
> use multiple runs if-and-only-if they want it. Hate to cite the lowest
> common denominator, but this was a very nasty surprise.
>
>
>
> On Wed, Sep 22, 2010 at 7:50 AM, Jeff Squyres <jsquyres_at_[hidden]> wrote:
>
> > Some of you may be unaware that recent versions of automake can run in
> > parallel. That is, automake will run in parallel with a degree of (at most)
> > $AUTOMAKE_JOBS. This can speed up the execution time of autogen.pl quite
> > a bit on some platforms. On my cluster at cisco, here's a few quick timings
> > of the entire autogen.pl process (of which, automake is the bottleneck):
> >
> > $AUTOMAKE_JOBS Total wall time
> > value of autogen.pl
> > 8 3:01.46
> > 4 2:55.57
> > 2 3:28.09
> > 1 4:38.44
> >
> > This is an older Xeon machine with 2 sockets, each with 2 cores.
> >
> > There's a nice performance jump from 1 to 2, and a smaller jump from 2 to
> > 4. 4 and 8 are close enough to not matter. YMMV.
> >
> > I just committed a heuristic to autogen.pl to setenv AUTOMAKE_JOBS if it
> > is not already set (https://svn.open-mpi.org/trac/ompi/changeset/23788):
> >
> > - If lstopo is found in your $PATH, runs it and count how many PU's
> > (processing units) you have. It'll set AUTOMAKE_JOBS to that number, or a
> > maximum of 4 (which is admittedly a further heuristic).
> > - If lstopo is not found, it just sets AUTOMAKE_JOBS to 2.
> >
> > Enjoy.
> >
> > --
> > Jeff Squyres
> > jsquyres_at_[hidden]
> > For corporate legal information go to:
> > http://www.cisco.com/web/about/doing_business/legal/cri/