Re: parallelizing more actions

[Efraim Flashner <efraim@flashner.co.il>]

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On Sun, Nov 12, 2017 at 03:31:49PM +0200, Efraim Flashner wrote:
> On Thu, Nov 09, 2017 at 11:05:59AM +0200, Efraim Flashner wrote:
> > While rebuilding glibc-final on aarch64 I realized that the 'strip phase
> > took 235 seconds. The relevant code for 'strip from gnu-build-system is
> > in guix/build/gnu-build-system.scm, starting at line 340, with the
> > actual stripping starting at 398. When I changed 'for-each' to
> > 'par-for-each' the time dropped from 235 seconds to 215, about an 8.5%
> > savings. I'm pretty sure most of that time was spent failing to strip
> > certain files, but it is still a savings.
> > 
> 
> These numbers were for glibc@2.26. I ran it against glibc@2.25 on my
> x86_64 machine with a spinning harddrive and 2 cores, without the patch
> it took 165.7 seconds (164.6 the second time), with the patch it dropped
> to 24.3 seconds.
> 
> I'll test it with glibc@2.25 on aarch64 later when its not building
> other things.
> 

Looks like aarch64 could use some help somewhere. With the patch it took
221.9 seconds, without the patch it was 219.8.

so in summary, aarch64 is terrible at stripping, parallel or not, and on
x86_64 my patch saved 85% of the patching time, despite only using 2 cores.


both versions for aarch64 had many lines like:
strip: /gnu/store/gslfpqdmgbwb5ryilq33bn9vs1466fn2-glibc-2.25-debug/lib/debug//gnu/store/7iihk77hqvsqjx7dnb19237dg4xgqvis-glibc-2.25/lib/stSy721B/fgetws_chk.o: no group info for section .data.DW.ref.__gcc_personality_v0


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Efraim Flashner   <efraim@flashner.co.il>   אפרים פלשנר
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