[OMPI users] --enable-builtin-atomics

[Dave Love]

So far only cons. The gcc and sync builtin atomic provide slower
performance on x86-64 (and possible other platforms). I plan to
investigate this as part of the investigation into requiring C11
atomics from the C compiler.

Thanks. Is that a gcc deficiency, or do the intrinsics just do
something different (more extensive)?

[Barrett, Brian via users]

Well, if you’re trying to get Open MPI running on a platform for which we don’t have atomics support, built-in atomics solves a problem for you…

Brian

So far only cons. The gcc and sync builtin atomic provide slower performance on x86-64 (and possible other platforms). I plan to investigate this as part of the investigation into requiring C11 atomics from the C compiler.
-Nathan

What are the pros and cons of configuring with --enable-builtin-atomics?
I haven't spotted any discussion of the option.
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[Dave Love]

Post by Barrett, Brian via users
Well, if you’re trying to get Open MPI running on a platform for which
we don’t have atomics support, built-in atomics solves a problem for
you…

That's not an issue in this case, I think. (I'd expect it to default to
intrinsic if extrinsic support is missing.)