Re: fftw runtime cpu detection

[ludovic.courtes@inria.fr (Ludovic Courtès)]

Eric Bavier <bavier@cray.com> skribis:

> On Fri, Apr 06, 2018 at 10:05:43AM +0200, Ludovic Courtès wrote:
>> Hello Eric,
>> 
>> Eric Bavier <bavier@cray.com> 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.

OK.

>> 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?

If Marius has no objections, I think you could push it directly to
core-updates.

Thank you,
Ludo’.