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Subject: [bug#31015] [PATCH] packages, scripts,
	utils: Respect (parallel-job-count) when xz-compressing.
Resent-Message-ID: <handler.31015.B31015.152284212626473@debbugs.gnu.org>
From: ludo@gnu.org (Ludovic =?UTF-8?Q?Court=C3=A8s?=)
References: <20180401125431.11996-1-mbakke@fastmail.com>
Date: Wed, 04 Apr 2018 13:42:01 +0200
In-Reply-To: <20180401125431.11996-1-mbakke@fastmail.com> (Marius Bakke's
	message of "Sun, 1 Apr 2018 14:54:31 +0200")
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To: Marius Bakke <mbakke@fastmail.com>
Cc: 31015@debbugs.gnu.org

Hello!

Marius Bakke <mbakke@fastmail.com> skribis:

> * guix/packages.scm (patch-and-repack): When invoking 'xz', tell it to us=
e the
> amount of cores specified by e.g. 'guix build -c'.
> * guix/scripts/pack.scm (%compressors, bootstrap-xz): Likewise.  While at=
 it,
> use the long form '--threads=3D' for clarity.
> * guix/utils.scm (decompressed-port, compressed-port, compressed-output-p=
ort):
> Likewise.

Wasn=E2=80=99t there an issue that parallel xz is non-deterministic?  I vag=
uely
remember something like this when we were producing with glibc tarballs
out of the Git repo.

If so, we should instead use -T1, even if that means getting worse
performance (I hear that lzip =E2=80=9Cworks better=E2=80=9D than xz, so we=
 should give
it a try if we want both performance and good compression.)

Besides, the guix/packages.scm part would lead to a full rebuild, so I
think it=E2=80=99s a bit late for =E2=80=98core-updates=E2=80=99.

Thanks,
Ludo=E2=80=99.