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From: Junio C Hamano <gitster@pobox.com>
To: Patrick Steinhardt <ps@pks.im>
Cc: git@vger.kernel.org, "Jeff King" <peff@peff.net>,
	"Felipe Contreras" <felipe.contreras@gmail.com>,
	"SZEDER Gábor" <szeder.dev@gmail.com>,
	"Chris Torek" <chris.torek@gmail.com>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"Taylor Blau" <me@ttaylorr.com>
Subject: Re: [PATCH v3 3/4] revision: avoid loading object headers multiple times
Date: Mon, 02 Aug 2021 12:40:56 -0700	[thread overview]
Message-ID: <xmqq5ywnws6v.fsf@gitster.g> (raw)
In-Reply-To: <b9897e102afbcab3bfee58ed8bda24257d8b54fb.1627896460.git.ps@pks.im> (Patrick Steinhardt's message of "Mon, 2 Aug 2021 11:38:10 +0200")

Patrick Steinhardt <ps@pks.im> writes:

> When loading references, we try to optimize loading of commits by using
> the commit graph. To do so, we first need to determine whether the
> object actually is a commit or not, which is why we always execute
> `oid_object_info()` first. Like this, we'll unpack the object header of
> each object first.
>
> This pattern can be quite inefficient in case many references point to
> the same commit: if the object didn't end up in the cached objects, then
> we'll repeatedly unpack the same object header, even if we've already
> seen the object before.
> ...
> Assuming that in almost all repositories, most references will point to
> either a tag or a commit, we'd have a modest increase in memory
> consumption of about 12.5% here.

I wonder if we can also say almost all repositories, the majority of
refs point at the same object.  If that holds, this would certainly
be a win, but otherwise, it is not so clear.

  parent reply	other threads:[~2021-08-02 19:41 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-28  5:33 [PATCH v2 0/3] Speed up connectivity checks via bitmaps Patrick Steinhardt
2021-06-28  5:33 ` [PATCH v2 1/3] p5400: add perf tests for git-receive-pack(1) Patrick Steinhardt
2021-06-28  7:49   ` Ævar Arnfjörð Bjarmason
2021-06-29  6:18     ` Patrick Steinhardt
2021-06-29 12:09       ` Ævar Arnfjörð Bjarmason
2021-06-28  5:33 ` [PATCH v2 2/3] receive-pack: skip connectivity checks on delete-only commands Patrick Steinhardt
2021-06-28  8:00   ` Ævar Arnfjörð Bjarmason
2021-06-28  8:06     ` Ævar Arnfjörð Bjarmason
2021-06-29  6:26     ` Patrick Steinhardt
2021-06-30  1:31   ` Jeff King
2021-06-30  1:35     ` Jeff King
2021-06-30 13:52     ` Patrick Steinhardt
2021-06-28  5:33 ` [PATCH v2 3/3] connected: implement connectivity check using bitmaps Patrick Steinhardt
2021-06-28 20:23   ` Taylor Blau
2021-06-29 22:44     ` Taylor Blau
2021-06-30  2:04       ` Jeff King
2021-06-30  3:07         ` Taylor Blau
2021-06-30  5:45           ` Jeff King
2021-07-02 17:44             ` Taylor Blau
2021-07-02 21:21               ` Jeff King
2021-06-30  1:51   ` Jeff King
2021-07-20 14:26     ` Patrick Steinhardt
2021-08-02  9:37 ` [PATCH v3 0/4] Speed up connectivity checks Patrick Steinhardt
2021-08-02  9:38   ` [PATCH v3 1/4] connected: do not sort input revisions Patrick Steinhardt
2021-08-02 12:49     ` Ævar Arnfjörð Bjarmason
2021-08-03  8:50       ` Patrick Steinhardt
2021-08-04 11:01         ` Ævar Arnfjörð Bjarmason
2021-08-02 19:00     ` Junio C Hamano
2021-08-03  8:55       ` Patrick Steinhardt
2021-08-03 21:47         ` Junio C Hamano
2021-08-02  9:38   ` [PATCH v3 2/4] revision: stop retrieving reference twice Patrick Steinhardt
2021-08-02 12:53     ` Ævar Arnfjörð Bjarmason
2021-08-02  9:38   ` [PATCH v3 3/4] revision: avoid loading object headers multiple times Patrick Steinhardt
2021-08-02 12:55     ` Ævar Arnfjörð Bjarmason
2021-08-05 10:12       ` Patrick Steinhardt
2021-08-02 19:40     ` Junio C Hamano [this message]
2021-08-03  9:07       ` Patrick Steinhardt
2021-08-06 14:17         ` Patrick Steinhardt
2021-08-02  9:38   ` [PATCH v3 4/4] revision: avoid hitting packfiles when commits are in commit-graph Patrick Steinhardt
2021-08-02 20:01     ` Junio C Hamano
2021-08-03  9:16       ` Patrick Steinhardt
2021-08-03 21:56         ` Junio C Hamano
2021-08-05 11:01           ` Patrick Steinhardt
2021-08-05 16:16             ` Junio C Hamano
2021-08-04 10:51         ` Ævar Arnfjörð Bjarmason
2021-08-05 11:25   ` [PATCH v4 0/6] Speed up connectivity checks Patrick Steinhardt
2021-08-05 11:25     ` [PATCH v4 1/6] revision: separate walk and unsorted flags Patrick Steinhardt
2021-08-05 18:47       ` Junio C Hamano
2021-08-05 11:25     ` [PATCH v4 2/6] connected: do not sort input revisions Patrick Steinhardt
2021-08-05 18:44       ` Junio C Hamano
2021-08-06  6:00         ` Patrick Steinhardt
2021-08-06 16:50           ` Junio C Hamano
2021-08-05 11:25     ` [PATCH v4 3/6] revision: stop retrieving reference twice Patrick Steinhardt
2021-08-05 11:25     ` [PATCH v4 4/6] revision: avoid loading object headers multiple times Patrick Steinhardt
2021-08-05 11:25     ` [PATCH v4 5/6] commit-graph: split out function to search commit position Patrick Steinhardt
2021-08-05 11:25     ` [PATCH v4 6/6] revision: avoid hitting packfiles when commits are in commit-graph Patrick Steinhardt
2021-08-09  8:00 ` [PATCH v5 0/5] Speed up connectivity checks Patrick Steinhardt
2021-08-09  8:02   ` Patrick Steinhardt
2021-08-09  8:11 ` Patrick Steinhardt
2021-08-09  8:11   ` [PATCH v5 1/5] revision: separate walk and unsorted flags Patrick Steinhardt
2021-08-09  8:11   ` [PATCH v5 2/5] connected: do not sort input revisions Patrick Steinhardt
2021-08-09  8:11   ` [PATCH v5 3/5] revision: stop retrieving reference twice Patrick Steinhardt
2021-08-09  8:11   ` [PATCH v5 4/5] commit-graph: split out function to search commit position Patrick Steinhardt
2021-08-09  8:12   ` [PATCH v5 5/5] revision: avoid hitting packfiles when commits are in commit-graph Patrick Steinhardt

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