From: "Ævar Arnfjörð Bjarmason" <email@example.com> To: Jeff King <firstname.lastname@example.org> Cc: Git Mailing List <email@example.com> Subject: Re: upload-pack is slow with lots of refs Date: Thu, 4 Oct 2012 01:47:00 +0200 [thread overview] Message-ID: <CACBZZX764OOH82CiLYPr+_qNU65U4Zxuod_7G5ef8yAtHApXog@mail.gmail.com> (raw) In-Reply-To: <20121003232115.GB11618@sigill.intra.peff.net> On Thu, Oct 4, 2012 at 1:21 AM, Jeff King <firstname.lastname@example.org> wrote: > On Thu, Oct 04, 2012 at 12:32:35AM +0200, Ævar Arnfjörð Bjarmason wrote: > >> On Wed, Oct 3, 2012 at 8:03 PM, Jeff King <email@example.com> wrote: >> > What version of git are you using? In the past year or so, I've made >> > several tweaks to speed up large numbers of refs, including: >> > >> > - cff38a5 (receive-pack: eliminate duplicate .have refs, v1.7.6); note >> > that this only helps if they are being pulled in by an alternates >> > repo. And even then, it only helps if they are mostly duplicates; >> > distinct ones are still O(n^2). >> > >> > - 7db8d53 (fetch-pack: avoid quadratic behavior in remove_duplicates) >> > a0de288 (fetch-pack: avoid quadratic loop in filter_refs) >> > Both in v1.7.11. I think there is still a potential quadratic loop >> > in mark_complete() >> > >> > - 90108a2 (upload-pack: avoid parsing tag destinations) >> > 926f1dd (upload-pack: avoid parsing objects during ref advertisement) >> > Both in v1.7.10. Note that tag objects are more expensive to >> > advertise than commits, because we have to load and peel them. >> > >> > Even with those patches, though, I found that it was something like ~2s >> > to advertise 100,000 refs. >> >> FWIW I bisected between 1.7.9 and 1.7.10 and found that the point at >> which it went from 1.5/s to 2.5/s upload-pack runs on the pathological >> git.git repository was none of those, but: >> >> ccdc6037fe - parse_object: try internal cache before reading object db > > Ah, yeah, I forgot about that one. That implies that you have a lot of > refs pointing to the same objects (since the benefit of that commit is > to avoid reading from disk when we have already seen it). > > Out of curiosity, what does your repo contain? I saw a lot of speedup > with that commit because my repos are big object stores, where we have > the same duplicated tag refs for every fork of the repo. Things are much faster with your monkeypatch, got up to around 10 runs/s. The repository mainly contains a lot of git-deploy generated tags which are added for every rollout to several subsystems. Of the ~50k references in the repo 75% point to a commit that no other reference points to. Around 98% of the references are annotated tags, the rest are branches. 1. https://github.com/git-deploy/git-deploy
next prev parent reply other threads:[~2012-10-04 21:53 UTC|newest] Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-10-03 12:36 Ævar Arnfjörð Bjarmason 2012-10-03 13:06 ` Nguyen Thai Ngoc Duy 2012-10-03 18:03 ` Jeff King 2012-10-03 18:53 ` Junio C Hamano 2012-10-03 18:55 ` Jeff King 2012-10-03 19:41 ` Shawn Pearce 2012-10-03 20:13 ` Jeff King 2012-10-04 21:52 ` Sascha Cunz 2012-10-05 0:20 ` Jeff King 2012-10-05 6:24 ` Johannes Sixt 2012-10-05 16:57 ` Shawn Pearce 2012-10-08 15:05 ` Johannes Sixt 2012-10-09 6:46 ` Shawn Pearce 2012-10-09 20:30 ` Johannes Sixt 2012-10-09 20:46 ` Johannes Sixt 2012-10-03 20:16 ` Ævar Arnfjörð Bjarmason 2012-10-03 21:20 ` Jeff King 2012-10-03 22:15 ` Ævar Arnfjörð Bjarmason 2012-10-03 23:15 ` Jeff King 2012-10-03 23:54 ` Ævar Arnfjörð Bjarmason 2012-10-04 7:56 ` [PATCH 0/4] optimizing upload-pack ref peeling Jeff King 2012-10-04 7:58 ` [PATCH 1/4] peel_ref: use faster deref_tag_noverify Jeff King 2012-10-04 18:24 ` Junio C Hamano 2012-10-04 8:00 ` [PATCH 2/4] peel_ref: do not return a null sha1 Jeff King 2012-10-04 18:32 ` Junio C Hamano 2012-10-04 8:02 ` [PATCH 3/4] peel_ref: check object type before loading Jeff King 2012-10-04 19:06 ` Junio C Hamano 2012-10-04 19:41 ` Jeff King 2012-10-04 20:41 ` Junio C Hamano 2012-10-04 21:59 ` Jeff King 2012-10-04 8:03 ` [PATCH 4/4] upload-pack: use peel_ref for ref advertisements Jeff King 2012-10-04 8:04 ` [PATCH 0/4] optimizing upload-pack ref peeling Jeff King 2012-10-04 9:01 ` Ævar Arnfjörð Bjarmason 2012-10-04 12:14 ` Nazri Ramliy 2012-10-03 22:32 ` upload-pack is slow with lots of refs Ævar Arnfjörð Bjarmason 2012-10-03 23:21 ` Jeff King 2012-10-03 23:47 ` Ævar Arnfjörð Bjarmason [this message] 2012-10-03 19:13 ` Junio C Hamano
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