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Subject: Re: [OMPI devel] GCC atomic intrinsics
From: Paul H. Hargrove (PHHargrove_at_[hidden])
Date: 2010-07-20 12:05:54


One thing to note is that the GCC atomic intrinsics are not always
implemented either. Use of an intrinsic that is unimplemented in a
given GCC version for a given platform will result in an link failure
(trying to call an "external" implementation that probably does not
exist). So, even if this leads to support for MORE platforms, it is not
certain to magically produce support for ALL platforms on which GCC is
available.

In addition of the OpenPA project, there are also atomics for a wide
variety of platforms (including the explicitly mentioned MIPS and ARM)
in GASNet Tools.

-Paul

Jeff Squyres wrote:
> *** This mail mainly targeted at Brian and George ***
>
> Debian maintainer Manuel Prinz raised an idea to me this morning:
>
> The Debian community compiles and tests Debian on a huge range of hardware platforms. It's been a long-standing issue that Open MPI doesn't support all of them (e.g., MIPS, ARM, ...). Specifically, we don't have assembly to support all of those platforms.
>
> The Debian community asks: if building with a recent GCC on one of these platforms where OMPI doesn't have native assembly, can we fall back to the GCC intrinsic atomics?
>
> https://svn.open-mpi.org/trac/ompi/ticket/2495
>
> Additionally, there's then OpenPA project from Argonne that supports a bunch of atomics on a bunch of platforms. George told me at one point that he didn't think it was sufficient for Open MPI's needs. Do we know if that's still true?
>
>

-- 
Paul H. Hargrove                          PHHargrove_at_[hidden]
Future Technologies Group
HPC Research Department                   Tel: +1-510-495-2352
Lawrence Berkeley National Laboratory     Fax: +1-510-486-6900