From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ricardo Wurmus Subject: bug#24937: "deleting unused links" GC phase is too slow Date: Tue, 13 Dec 2016 18:18:57 +0100 Message-ID: <87vaunbvcu.fsf@mdc-berlin.de> References: <87wpg7ffbm.fsf@gnu.org> <87lgvm4lzu.fsf@gnu.org> <87twaaa6j9.fsf@netris.org> <87twaa2vjx.fsf@gnu.org> <87lgvm9sgq.fsf@netris.org> <87d1gwvgu0.fsf@gnu.org> <87wpf4yoz0.fsf@netris.org> <87fulrsqxx.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Return-path: Received: from eggs.gnu.org ([2001:4830:134:3::10]:49847) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cGqkI-000053-7J for bug-guix@gnu.org; Tue, 13 Dec 2016 12:20:07 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cGqkE-0007Oa-7y for bug-guix@gnu.org; Tue, 13 Dec 2016 12:20:06 -0500 Received: from debbugs.gnu.org ([208.118.235.43]:53793) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1cGqkE-0007OS-49 for bug-guix@gnu.org; Tue, 13 Dec 2016 12:20:02 -0500 Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1cGqkD-0001d5-Py for bug-guix@gnu.org; Tue, 13 Dec 2016 12:20:01 -0500 Sender: "Debbugs-submit" Resent-Message-ID: In-Reply-To: <87fulrsqxx.fsf@gnu.org> List-Id: Bug reports for GNU Guix List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-guix-bounces+gcggb-bug-guix=m.gmane.org@gnu.org Sender: "bug-Guix" To: Ludovic =?UTF-8?Q?Court=C3=A8s?= Cc: 24937@debbugs.gnu.org Ludovic Courtès writes: > Ricardo, Roel: would you be able to run that links-traversal.c from > > on a machine with a big store, as described at > ? I just ran this on my workstation in the office where I regularly build packages. Here’s the output of “df -i /gnu” Filesystem Inodes IUsed IFree IUse% Mounted on /dev/mapper/fedora-root 3301376 1098852 2202524 34% / Probably not large enough to derive conclusions about hydra’s behaviour. [I can’t run it on the shared store at the MDC because NFS performance is too poor. I recently ran “guix gc --optimize” to dedupe the shared store (post-build deduplication is disabled since a few weeks) and it’s at 3,197,489 used inodes.] Here are the results of running the link-traversal code on my workstation: --8<---------------cut here---------------start------------->8--- rwurmus in ~: gcc -std=gnu99 -Wall links-traversal.c -DMODE=3 rwurmus in ~: sudo sh -c 'echo 3 > /proc/sys/vm/drop_caches' rwurmus in ~: time ./a.out 412825 dir_entries, 107 seconds stat took 0 seconds real 1m47.264s user 0m0.214s sys 0m1.314s rwurmus in ~: gcc -std=gnu99 -Wall links-traversal.c -DMODE=2 rwurmus in ~: sudo sh -c 'echo 3 > /proc/sys/vm/drop_caches' rwurmus in ~: time ./a.out 12821 dir_entries, 107 seconds (including stat) real 1m46.475s user 0m0.201s sys 0m1.309s --8<---------------cut here---------------end--------------->8--- -- Ricardo