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From: ludo@gnu.org (Ludovic =?UTF-8?Q?Court=C3=A8s?=)
Subject: bug#24937: "deleting unused links" GC phase is too slow
Date: Sun, 13 Nov 2016 18:41:01 +0100
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To: 24937@debbugs.gnu.org

=E2=80=98LocalStore::removeUnusedLinks=E2=80=99 traverses all the entries in
/gnu/store/.links and calls lstat(2) on each one of them and checks
=E2=80=98st_nlink=E2=80=99 to determine whether they can be deleted.

There are two problems: lstat(2) can be slow on spinning disks as found
on hydra.gnu.org, and the algorithm is proportional in the number of
entries in /gnu/store/.links, which is a lot on hydra.gnu.org.

Ludo=E2=80=99.