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Re: fftw runtime cpu detection
From: |
Eric Bavier |
Subject: |
Re: fftw runtime cpu detection |
Date: |
Fri, 6 Apr 2018 10:02:32 -0500 |
User-agent: |
Mutt/1.5.17 (2007-11-01) |
On Fri, Apr 06, 2018 at 10:05:43AM +0200, Ludovic Courtès wrote:
> Hello Eric,
>
> Eric Bavier <address@hidden> skribis:
>
> > I recently discovered that the FFTW library can do runtime cpu
> > detection. In order to do this, the package needs to be configured to
> > build SIMD "codelets", like how our 'fftw-avx' currently does. Then,
> > based on the instruction support detected at runtime, make those
> > kernels available to the fftw "planner" for execution.
>
> That’s really good news! Thanks for testing it.
>
> The patch LGTM. Can you confirm that the planner won’t ever try to use
> the AVX2 codelets, for instance when running the test suite on an x86_64
> box that lacks AVX2?
Yes, I've successfully run 'make check' on an sse2-only machine where
'--enable-avx' and '--enable-avx2' where configured. I'll check on an
i686 machine tonight.
> If that’s the case, I’d be in favor of pushing this patch to core-updates.
Great. I'll do some more testing. Should I send a finalized patch to
guix-patches when it's ready?
--
Eric Bavier, Scientific Libraries, Cray Inc.