[torqueusers] Changing --with-debug to the default

Michael Jennings mej at lbl.gov
Tue Jul 31 14:17:15 MDT 2012


On Tuesday, 31 July 2012, at 13:56:53 (-0600),
David Beer wrote:

> Would you still think its worth it to separate these if I told you
> that the default would be without optimization as well? The benefits
> of having debugging symbols are compromised if optimizations are on,
> as you point out.

Compromised, but not eliminated entirely.  -O0 -g3 is the most useful,
but -O2 -g3 is more useful than -O2.  :-)

I'm still in favor of them being split up regardless.  That way, a
particular site can make the choice between larger binaries with
symbols (-g3) vs. smaller binaries with addresses only (-g0) entirely
independent of the decision between higher (-O1/2/3/s) and lower (-O0)
performance.

As you know, adding debugging symbols has no effect on performance,
but disabling optimization almost certainly would.  :-)  For our site,
we haven't noticed a performance penalty from the -O0 -g3 packages
I've built over the last couple weeks, but that doesn't mean other
sites won't see one.

Have you all done any performance testing between the various
optimization levels?  That might give you some valuable insights into
the implications of what you're proposing....  :-)

Michael

-- 
Michael Jennings <mej at lbl.gov>
Senior HPC Systems Engineer
High-Performance Computing Services
Lawrence Berkeley National Laboratory
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