From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org, "Shawn O. Pearce" <spearce@spearce.org>
Subject: Re: [PATCH 2/2] pack-objects: optimize "recency order"
Date: Thu, 27 Oct 2011 23:49:14 +0200 [thread overview]
Message-ID: <CACBZZX6ZWOF=j-k8o-4NHmjS2HpyS+PmKjJh_QKevWurBf9pbA@mail.gmail.com> (raw)
In-Reply-To: <CACBZZX6Ss4jLtdrDhLUNKCUjEHjHHKzfv-LMkOyTPDhRUXm4sQ@mail.gmail.com>
On Thu, Oct 27, 2011 at 23:01, Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:
> I haven't dug into why this is but I'm pretty sure it's because this
> patch makes Git behave pathologically on repositories with a large
> amount of tags. git.git itself has ~27k revs / and ~450 tags, or a tag
> every ~60 revisions.
>
> Try it on e.g. a repository with a couple of hundred thousand revs and
> a tag every 10-20 revisions.
Actually it just seems slow in general, not just on repositories with
a lot of tags, on linux-2.6.git with this patch:
$ time ~/g/git/git-pack-objects --keep-true-parents
--honor-pack-keep --non-empty --all --reflog
--delta-base-offs</dev/null
/home/avar/g/linux-2.6/.git/objects/pack/.tmp-pack
Counting objects: 2184059, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (338780/338780), done.
130605d5b82492a38452b9bc7bddfb4a6ef0e942
Writing objects: 100% (2184059/2184059), done.
Total 2184059 (delta 1825129), reused 2184059 (delta 1825129)
real 1m28.426s
user 1m19.661s
sys 0m3.008s
With it reverted:
$ time ~/g/git/git-pack-objects --keep-true-parents
--honor-pack-keep --non-empty --all --reflog --delta-base-offset
</dev/null /home/avar/g/linux-2.6/.git/objects/pack/.tmp-pack
Counting objects: 2184059, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (338780/338780), done.
130605d5b82492a38452b9bc7bddfb4a6ef0e942
Writing objects: 100% (2184059/2184059), done.
Total 2184059 (delta 1825129), reused 2184059 (delta 1825129)
real 0m50.152s
user 0m45.367s
sys 0m2.920s
And if you create a lot of tags:
git log --pretty=%h | perl -lne 'chomp(my $sha = <>); print $sha
if $i++ % 10 == 0' | parallel "git tag test-tag-{} {}"
Resulting in:
$ git rev-list HEAD | wc -l
269514
$ git tag -l | wc -l
13733
This'll be the time with this patch reverted, i.e. almost exactly the
same as with just ~250 tags:
real 0m52.860s
user 0m44.907s
sys 0m3.172s
And with it applied, i.e. almost exactly the same as with just ~250
tags:
real 1m29.080s
user 1m21.825s
sys 0m3.096s
next prev parent reply other threads:[~2011-10-27 21:49 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-08 0:24 [PATCH 0/2] For improved pack locality Junio C Hamano
2011-07-08 0:24 ` [PATCH 1/2] core: log offset pack data accesses happened Junio C Hamano
2011-07-08 0:24 ` [PATCH 2/2] pack-objects: optimize "recency order" Junio C Hamano
2011-07-08 2:08 ` Shawn Pearce
2011-07-08 17:45 ` Junio C Hamano
2011-07-11 22:49 ` Nicolas Pitre
2011-07-08 22:47 ` Junio C Hamano
2011-07-09 0:42 ` Shawn Pearce
2011-10-27 21:01 ` Ævar Arnfjörð Bjarmason
2011-10-27 21:49 ` Ævar Arnfjörð Bjarmason [this message]
2011-10-27 22:02 ` Ævar Arnfjörð Bjarmason
2011-10-27 22:32 ` Jakub Narebski
2011-10-27 22:05 ` Junio C Hamano
2011-10-28 9:17 ` Ævar Arnfjörð Bjarmason
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