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Subject: Re: [OMPI users] memcpy overlap in ompi_ddt_copy_content_same_ddt and glibc 2.12
From: Jed Brown (jed_at_[hidden])
Date: 2010-11-10 12:25:51


On Wed, Nov 10, 2010 at 18:11, Number Cruncher <number.cruncher_at_[hidden]
> wrote:

> Just some observations from a concerned user with a temperamental Open MPI
> program (1.4.3):
>
> Fedora 14 (just released) includes glibc-2.12 which has optimized versions
> of memcpy, including a copy backward.
>
> http://sourceware.org/git/?p=glibc.git;a=commitdiff;h=6fb8cbcb58a29fff73eb2101b34caa19a7f88eba

Is the memcpy-back code ever executed when called as memcpy()? I can't
imagine why it would be, but it would make plenty of sense to use it inside
memmove when the destination is at a higher address than the source.

Jed