glibc 2.33's HWCAPS and GCC Function Multiversioning for performance

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3 participants
  • Léo Le Bouter
  • Ludovic Courtès
  • Ludovic Courtès
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Submitted by
Léo Le Bouter
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normal
L
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Léo Le Bouter wrote on 17 Mar 2021 19:59
(address . bug-guix@gnu.org)
f63bb1764b53c6b5c7e959281d522cd0c24bd8f3.camel@zaclys.net
Hello!

Please see:
-

This could help GNU Guix create binaries that include multiple code
paths for several CPU features in the same binary and selecting the
best at runtime when the binary is run.

It is the best fit for GNU Guix because it means we can still use
substitutes and profit from specialized optimizations without
parameterized packages or each user adding "-march=native" to CFLAGS
(breaking reproducibility).

Léo
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L
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Ludovic Courtès wrote on 18 Mar 2021 14:17
(name . Léo Le Bouter)(address . lle-bout@zaclys.net)(address . 47218@debbugs.gnu.org)
87lfakr47d.fsf@gnu.org
Hi Léo,

Léo Le Bouter <lle-bout@zaclys.net> skribis:

Toggle quote (15 lines)
> Please see:
> -
> https://www.gnu.org/software/libc/manual/html_mono/libc.html#Hardware-Capability-Tunables
> - https://www.phoronix.com/scan.php?page=news_item&px=glibc-hwcaps-RFC
> - https://gcc.gnu.org/onlinedocs/gcc/Function-Multiversioning.html
>
> This could help GNU Guix create binaries that include multiple code
> paths for several CPU features in the same binary and selecting the
> best at runtime when the binary is run.
>
> It is the best fit for GNU Guix because it means we can still use
> substitutes and profit from specialized optimizations without
> parameterized packages or each user adding "-march=native" to CFLAGS
> (breaking reproducibility).

For the record, we are well aware of these features and follow this very
closely in particular in the context of Guix-HPC:


It seems to me that this bug report is not actionable though. Unless
there are concrete steps you’d like to suggest, I propose to close this
issue.

Thanks,
Ludo’.
L
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Ludovic Courtès wrote on 29 Mar 2021 23:40
control message for bug #47218
(address . control@debbugs.gnu.org)
87ft0dljv0.fsf@gnu.org
tags 47218 notabug
close 47218
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