From: Patrick Steinhardt <ps@pks.im>
To: Junio C Hamano <gitster@pobox.com>
Cc: "Derrick Stolee" <stolee@gmail.com>,
git@vger.kernel.org, "Jeff King" <peff@peff.net>,
"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Subject: Re: [PATCH 1/6] fetch: speed up lookup of want refs via commit-graph
Date: Mon, 23 Aug 2021 08:46:27 +0200 [thread overview]
Message-ID: <YSNEQ9R0TDUNPZPM@ncase> (raw)
In-Reply-To: <xmqq7dggvxup.fsf@gitster.g>
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On Fri, Aug 20, 2021 at 10:18:22AM -0700, Junio C Hamano wrote:
> Derrick Stolee <stolee@gmail.com> writes:
>
> > I do worry about the case where annotated tags greatly outnumber
> > branches, so this binary search is extra overhead and the performance
> > may degrade. Would it be worth checking the ref to see if it lies
> > within "refs/heads/" (or even _not_ in "refs/tags/") before doing
> > this commit-graph check?
>
> Ah, clever.
Good idea. Benchmarks for my test repository (which definitely isn't
representative, but it's at least some numbers) show that restricting to
"refs/heads/" diminishes almost all the gains, while restricting to
everything but "refs/tags/" performs almost the same (it's a tiny bit
slower, probably because of the added string comparisons):
Benchmark #1: all refs: git-fetch
Time (mean ± σ): 32.959 s ± 0.282 s [User: 29.801 s, System: 5.137 s]
Range (min … max): 32.760 s … 33.158 s 2 runs
Benchmark #2: refs/heads: git-fetch
Time (mean ± σ): 56.955 s ± 0.002 s [User: 53.447 s, System: 5.362 s]
Range (min … max): 56.953 s … 56.957 s 2 runs
Benchmark #3: !refs/tags: git-fetch
Time (mean ± σ): 33.447 s ± 0.003 s [User: 30.160 s, System: 5.027 s]
Range (min … max): 33.444 s … 33.449 s 2 runs
Summary
'all refs: git-fetch' ran
1.01 ± 0.01 times faster than '!refs/tags: git-fetch'
1.73 ± 0.01 times faster than 'refs/heads: git-fetch'
This is easily explained by the fact that the test repo has most of its
refs neither in "refs/tags/" nor in "refs/heads/", but rather in special
namespaces like "refs/merge-requests/", "refs/environments/" or
"refs/keep-around/".
I like the idea of excluding "refs/tags/" though: as you point out,
chances are high that these don't point to commits but to annotated tags
instead. So I'll go with that, thanks!
Patrick
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next prev parent reply other threads:[~2021-08-23 6:46 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-20 10:08 [PATCH 0/6] Speed up mirror-fetches with many refs Patrick Steinhardt
2021-08-20 10:08 ` [PATCH 1/6] fetch: speed up lookup of want refs via commit-graph Patrick Steinhardt
2021-08-20 14:27 ` Derrick Stolee
2021-08-20 17:18 ` Junio C Hamano
2021-08-23 6:46 ` Patrick Steinhardt [this message]
2021-08-25 14:12 ` Derrick Stolee
2021-08-20 10:08 ` [PATCH 2/6] fetch: avoid unpacking headers in object existence check Patrick Steinhardt
2021-08-25 23:44 ` Ævar Arnfjörð Bjarmason
2021-08-20 10:08 ` [PATCH 3/6] connected: refactor iterator to return next object ID directly Patrick Steinhardt
2021-08-20 14:32 ` Derrick Stolee
2021-08-20 17:43 ` Junio C Hamano
2021-08-20 17:43 ` René Scharfe
2021-08-23 6:47 ` Patrick Steinhardt
2021-08-20 10:08 ` [PATCH 4/6] fetch-pack: optimize loading of refs via commit graph Patrick Steinhardt
2021-08-20 14:37 ` Derrick Stolee
2021-08-20 10:08 ` [PATCH 5/6] fetch: refactor fetch refs to be more extendable Patrick Steinhardt
2021-08-20 14:41 ` Derrick Stolee
2021-08-20 10:08 ` [PATCH 6/6] fetch: avoid second connectivity check if we already have all objects Patrick Steinhardt
2021-08-20 14:47 ` Derrick Stolee
2021-08-23 6:52 ` Patrick Steinhardt
2021-08-20 14:50 ` [PATCH 0/6] Speed up mirror-fetches with many refs Derrick Stolee
2021-08-21 0:09 ` Junio C Hamano
2021-08-24 10:36 ` [PATCH v2 0/7] " Patrick Steinhardt
2021-08-24 10:36 ` [PATCH v2 1/7] fetch: speed up lookup of want refs via commit-graph Patrick Steinhardt
2021-08-25 14:16 ` Derrick Stolee
2021-08-24 10:37 ` [PATCH v2 2/7] fetch: avoid unpacking headers in object existence check Patrick Steinhardt
2021-08-24 10:37 ` [PATCH v2 3/7] connected: refactor iterator to return next object ID directly Patrick Steinhardt
2021-08-24 10:37 ` [PATCH v2 4/7] fetch-pack: optimize loading of refs via commit graph Patrick Steinhardt
2021-08-24 10:37 ` [PATCH v2 5/7] fetch: refactor fetch refs to be more extendable Patrick Steinhardt
2021-08-25 14:19 ` Derrick Stolee
2021-09-01 12:48 ` Patrick Steinhardt
2021-08-24 10:37 ` [PATCH v2 6/7] fetch: merge fetching and consuming refs Patrick Steinhardt
2021-08-25 14:26 ` Derrick Stolee
2021-09-01 12:49 ` Patrick Steinhardt
2021-08-24 10:37 ` [PATCH v2 7/7] fetch: avoid second connectivity check if we already have all objects Patrick Steinhardt
2021-08-24 22:48 ` [PATCH v2 0/7] Speed up mirror-fetches with many refs Junio C Hamano
2021-08-25 6:04 ` Patrick Steinhardt
2021-08-25 14:27 ` Derrick Stolee
2021-09-01 13:09 ` [PATCH v3 " Patrick Steinhardt
2021-09-01 13:09 ` [PATCH v3 1/7] fetch: speed up lookup of want refs via commit-graph Patrick Steinhardt
2021-09-01 13:09 ` [PATCH v3 2/7] fetch: avoid unpacking headers in object existence check Patrick Steinhardt
2021-09-01 13:09 ` [PATCH v3 3/7] connected: refactor iterator to return next object ID directly Patrick Steinhardt
2021-09-01 13:09 ` [PATCH v3 4/7] fetch-pack: optimize loading of refs via commit graph Patrick Steinhardt
2021-09-01 13:09 ` [PATCH v3 5/7] fetch: refactor fetch refs to be more extendable Patrick Steinhardt
2021-09-01 13:10 ` [PATCH v3 6/7] fetch: merge fetching and consuming refs Patrick Steinhardt
2021-09-01 13:10 ` [PATCH v3 7/7] fetch: avoid second connectivity check if we already have all objects Patrick Steinhardt
2021-09-01 19:58 ` [PATCH v3 0/7] Speed up mirror-fetches with many refs Junio C Hamano
2021-09-08 0:08 ` Junio C Hamano
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