Re: Poor performance of git describe in big repos

From: Ramkumar Ramachandra <artagnon@gmail.com>
Date: May 30, 2013, 11:33 UTC
Message-ID: <CALkWK0ndKMZRuWgdg6djqPUGxbDAqZPcv2q0qPrv_2b=1NEM5g@mail.gmail.com>
In-Reply-To: <CAJ-05NPQLVFhtb9KMLNLc5MqguBYM1=gKEVrrtT3kSMiZKma_g@mail.gmail.com>

Alex Bennée wrote:

Show 6 quoted lines

>>time /usr/bin/git --no-pager
> traversed 223 commits
>
> real    0m4.817s
> user    0m4.320s
> sys     0m0.464s

I'm quite clueless about why it is taking this long: I think it's IO because there's nothing to compute? I really can't trace anything unless you can reproduce it on a public repository. On linux.git with my rotating hard disk:

$ time git describe --debug --long --tags HEAD~10000
searching to describe HEAD~10000
 annotated       5445 v2.6.33
 annotated       5660 v2.6.33-rc8
 annotated       5884 v2.6.33-rc7
 annotated       6140 v2.6.33-rc6
 annotated       6467 v2.6.33-rc5
 annotated       6999 v2.6.33-rc4
 annotated       7430 v2.6.33-rc3
 annotated       7746 v2.6.33-rc2
 annotated       8212 v2.6.33-rc1
 annotated      13854 v2.6.32
traversed 18895 commits
more than 10 tags found; listed 10 most recent
gave up search at 648f4e3e50c4793d9dbf9a09afa193631f76fa26
v2.6.33-5445-ge7c84ee

real 0m0.509s user 0m0.470s sys 0m0.037s

18k+ commits traversed in half a second here, so I really don't know what is going on.