Gentoo Archives: gentoo-user

From: eroen <eroen@××××××××××××.eu>
To: gentoo-user@l.g.o
Subject: [gentoo-user] Re: --jobs is ignored for unmerging?
Date: Fri, 21 Feb 2014 14:56:43
Message-Id: 20140221155617.3c6f81f0@falcon.eroen.eu
In Reply to: [gentoo-user] --jobs is ignored for unmerging? by Nikos Chantziaras
1 On Fri, 21 Feb 2014 16:14:00 +0200, Nikos Chantziaras
2 <realnc@×××××.com> wrote:
3 > I recently needed to unmerge Netbeans and KDE from a machine. So
4 > removed the top-level packages of those, and then ran:
5 >
6 > emerge -a --depclean --jobs 20
7 >
8 > However, "--jobs" is being ignored. So I'm sitting there, watching
9 > hundreds of packages being unmerged one by one, taking a long time :-/
10 >
11 > Is this normal? Shouldn't the --jobs option result in emerge
12 > unmerging multiple packages at the same time?
13 >
14
15 From emerge(1)[1]:
16 -j [JOBS], --jobs[=JOBS]
17 Specifies the number of packages to build
18 simultaneously. (...)
19
20 In the past, unmerging was almost entirely IO bound, and running
21 several in parallel would have (at best) no significant speedup. I
22 suspect the (fairly recent) preserve-libs feature and detection of
23 unmodified configuration files introduced some cpu-intensive parts,
24 which might be parallelizeable to some extent if you sacrifice some of
25 the recoverability of an aborted unmerge.
26
27 If you can benchmark low IO utilization during unmerges, I suggest you
28 open a feature request bug on <bugs.gentoo.org> requesting parallel
29 unmerge. :-)
30
31 In the mean time, you might be able to speed the process up somewhat by
32 setting FEATURES="-merge-sync" in the environment when you do unmerges.
33 (see make.conf(5)[2])
34
35 1: https://dev.gentoo.org/~zmedico/portage/doc/man/emerge.1.html
36 2: https://dev.gentoo.org/~zmedico/portage/doc/man/make.conf.5.html
37
38 --
39 eroen

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