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From: ludo@gnu.org (Ludovic Courtès)
To: Efraim Flashner <efraim@flashner.co.il>
Cc: guix-devel@gnu.org
Subject: Re: parallelizing more actions
Date: Sat, 11 Nov 2017 12:25:01 +0100	[thread overview]
Message-ID: <878tfdjbw2.fsf@gnu.org> (raw)
In-Reply-To: <20171109090559.GF1815@macbook41> (Efraim Flashner's message of "Thu, 9 Nov 2017 11:05:59 +0200")

Hi Efraim,

Efraim Flashner <efraim@flashner.co.il> skribis:

> 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.

Is it on a spinning hard disk or an SSD?  My guess is that most of the
time is I/O, and that parallelizing doesn’t buy us much (indeed, 8.5% is
not that much, far from a linear speedup.) 

So I’m mildly reluctant to parallelizing this particular piece of code.

Thanks,
Ludo’.

  parent reply	other threads:[~2017-11-11 11:25 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-09  9:05 parallelizing more actions Efraim Flashner
2017-11-11  1:42 ` Chris Marusich
2017-11-11 11:25 ` Ludovic Courtès [this message]
2017-11-11 16:49   ` Efraim Flashner
2017-11-12 13:31 ` Efraim Flashner
2017-11-13 18:55   ` Efraim Flashner
2017-11-16 10:06     ` Ludovic Courtès

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