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Subject: Re: [OMPI devel] MALLOC_MMAP_MAX (and MALLOC_MMAP_THRESHOLD)
From: Sylvain Jeaugey (sylvain.jeaugey_at_[hidden])
Date: 2010-01-18 04:17:28


On Jan 17, 2010, at 11:31 AM, Ashley Pittman wrote:
> Tuning the libc malloc implementation using the options they provide to
> do is is valid and provides real benefit to a lot of applications. For
> the record we used to disable mmap based allocations by default on
> Quadrics systems and I can't think of a single case of people who needed
> to re-enable it.
It happened to me once. An application couldn't run (not enough memory)
because of the Quadrics stack setting the malloc options.

On Sun, 17 Jan 2010, Barrett, Brian W wrote:
> I'm glad that you've been so fortunate. Unfortunately, I have a large
> application base in which that is not the case, and we have had to use
> mmap based allocation, otherwise memory usage would essentially grow
> without bound. So we go back to the age-old debate of correctness vs.
> performance.
It would be interesting (though difficult) to know which proportion of
applications are suffering from these settings.

For my part, it is less than 1% (but not 0!).

Sylvain