Re: GCC "-fparallel-jobs" up to ~1.9x speedup when compiling individual files in parallel
On Sat, Aug 22, 2020 at 12:53:24PM +0200, Germano Massullo wrote:
I think soon we will have a big boost in Koji performances thanks to
Giuliano Belinassi and his work on addressing GCC parallelization
bottlenecks. According to Phoronix, compiling individual files in
parallel may have up to ~1.9x speedup:
https://www.phoronix.com/scan.php?page=news_item&px=GCC-fparallel-job...
AFAICT, that is referring to parallelizing single file compilation to
make use of multiple cores. That's only useful if the other cores on
your host are otherwise idle.
In koji we use parallel make (or equivalent) so that multiple files
are compiled in parallel. Thus most of the time all cores will be fully
utilized.
IOW, don't get too excited by the x1.9 speedup claim. I doubt we'll
see that in kojki except in niche scenarios where a project's build
is bottlenecked by a serialization point on compiling one file.
Regards,
Daniel
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