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Subject: Re: [OMPI devel] GCC atomic intrinsics
From: Barrett, Brian W (bwbarre_at_[hidden])
Date: 2010-07-20 12:12:29


Jeff -

I think falling back to GCC built-in if available is a rational idea. We've been using them in another project without any problems. They are potentially a bit slower than the hand-crafted assembly because they generally use full memory barriers when we only need read memory barriers, but that's not a bad thing for the portability case.

There's still an issue with the high resolution timers, but there are actually rational fall-backs for that, so we're probably ok there.

Brian

On Jul 20, 2010, at 9:49 AM, 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?
>
> --
> Jeff Squyres
> jsquyres_at_[hidden]
> For corporate legal information go to:
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>