RE: 01/01: gnu: fftw: Build SIMD codelets.

[Eric Bavier]

Ok, if you feel confident, that's fine with me.

Otherwise, I have a patch that I've tested on x86-64, and in the middle of 
testing for armhf that I can push in a few hours.  I could easily add a commit 
that remove the "--enable-armv7a-cntvct" flag.

Eric Bavier, Scientific Libraries, Cray Inc.


> -----Original Message-----
> From: Mark H Weaver [mailto:address@hidden
> Sent: Tuesday, May 08, 2018 3:57 PM
> To: Eric Bavier
> Cc: address@hidden
> Subject: Re: 01/01: gnu: fftw: Build SIMD codelets.
> 
> Hi Eric,
> 
> Mark H Weaver <address@hidden> writes:
> 
> > address@hidden (Eric Bavier) writes:
> >
> >> bavier pushed a commit to branch core-updates in repository guix.
> >>
> >> commit 65bb22796f854cbc3eae053a80b1d64365dad376
> >> Author: Eric Bavier <address@hidden>
> >> Date:   Fri Apr 6 10:53:06 2018 -0500
> >>
> >>     gnu: fftw: Build SIMD codelets.
> >>
> >>     * gnu/packages/algebra.scm (fftw)[arguments]: Remove 'no-native
> phase; use
> >>     configure cache value instead.  Add configure flags for SIMD codelets.
> >>     (fftwf)[arguments]: Add neon configuration flag for 32-bit arm.
> >>     (fftw-avx): Remove variable.
> >
> > [...]
> >
> >> @@ -560,7 +569,10 @@ cosine/ sine transforms or DCT/DST).")
> >>      (arguments
> >>       (substitute-keyword-arguments (package-arguments fftw)
> >>         ((#:configure-flags cf)
> >> -        `(cons "--enable-float" ,cf))))
> >> +        (if (string-prefix? "arm" (or (%current-target-system)
> >> +                                      (%current-system)))
> >> +            `(cons "--enable-neon" ,cf)
> >> +            cf))))
> >
> > Did you intend to remove the "--enable-float" configure flag in fftwf?
> > You didn't mention this change in the commit log.
> >
> > The description of fftwf appends "Single-precision version" to the
> > description from fftw, but since your commit above, the fftw and fftwf
> > packages are identical except on armhf, as far as I can tell.  On
> > armhf, the build now fails with "configure: error: NEON requires
> > single precision".
> >
> >   https://hydra.gnu.org/build/2674813/nixlog/1/tail-reload
> >
> > Can you take a look?
> 
> Another problem with the above commit has now become apparent.  In
> addition to the 'fftwf' failure at configuration time on armhf, the 'fftw'
> package also now fails its test suite on our armhf build slaves.
> While running the test suite, a test process is killed with SIGILL (Illegal
> instruction).
> 
> I looked into it, and it appears that the "--enable-armv7a-cntvct"
> configure flag that you added should be removed.  Adding it was a good
> guess, but apparently the ARMv7-a CNTVCT instruction is not available from
> user mode unless you use a specially patched kernel to enable it.
> 
> For details, see:
> 
>   https://github.com/FFTW/fftw3/blob/master/README-perfcnt.md
>   https://github.com/thoughtpolice/enable_arm_pmu
>   https://neocontra.blogspot.com/2013/05/user-mode-performance-
> counters-for.html
> 
> Since these issues are delaying the build-out of 'core-updates' on armhf
> with ~1K dependency failures, and I'm reasonably confident what needs to
> be done here, I'll go ahead and apply untested fixes for these issues to
> 'core-updates' soon.
> 
>      Regards,
>        Mark