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Subject: Re: [OMPI users] memcpy overlap in ompi_ddt_copy_content_same_ddt and glibc 2.12
From: George Bosilca (bosilca_at_[hidden])
Date: 2010-11-12 18:39:26


I think I have a solution which solve both issues:
 - deal with the overlapping regions
 - maintain the level of today's performance

Please try r24047.

  george.

On Nov 11, 2010, at 06:46 , Jed Brown wrote:

> On Thu, Nov 11, 2010 at 12:36, Number Cruncher <number.cruncher_at_[hidden]> wrote:
> However as commented here: https://bugzilla.redhat.com/show_bug.cgi?id=638477#c86 the valgrind memcpy implementation is overlap-safe.
>
> Yes, of course. That's how the bug in Open MPI was originally detected. Of course you can't do production runs with valgrind.
>
> Are you using an Intel Nehalem-class CPU?
>
> No, Core 2 Duo and Opteron (but the Opterons still have older glibc). Reverse memcpy must only be turned on for Nehalem.
>
> Jed
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