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Diffstat (limited to '_support/git-patches/v2.33.1.gl3/0001-fetch-pack-speed-up-loading-of-refs-via-commit-graph.patch')
| -rw-r--r-- | _support/git-patches/v2.33.1.gl3/0001-fetch-pack-speed-up-loading-of-refs-via-commit-graph.patch | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/_support/git-patches/v2.33.1.gl3/0001-fetch-pack-speed-up-loading-of-refs-via-commit-graph.patch b/_support/git-patches/v2.33.1.gl3/0001-fetch-pack-speed-up-loading-of-refs-via-commit-graph.patch new file mode 100644 index 000000000..23d0d6a33 --- /dev/null +++ b/_support/git-patches/v2.33.1.gl3/0001-fetch-pack-speed-up-loading-of-refs-via-commit-graph.patch @@ -0,0 +1,65 @@ +From 08519b8ab6f395cffbcd5e530bfba6aaf64241a2 Mon Sep 17 00:00:00 2001 +Message-Id: <08519b8ab6f395cffbcd5e530bfba6aaf64241a2.1628144240.git.ps@pks.im> +From: Patrick Steinhardt <ps@pks.im> +Date: Wed, 4 Aug 2021 15:04:25 +0200 +Subject: [PATCH] fetch-pack: speed up loading of refs via commit graph +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +When doing reference negotiation, git-fetch-pack(1) is loading all refs +from disk in order to determine which commits it has in common with the +remote repository. This can be quite expensive in repositories with many +references though: in a real-world repository with around 2.2 million +refs, fetching a single commit by its ID takes around 44 seconds. + +Dominating the loading time is decompression and parsing of the objects +which are referenced by commits. Given the fact that we only care about +commits (or tags which can be peeled to one) in this context, there is +thus an easy performance win by switching the parsing logic to make use +of the commit graph in case we have one available. Like this, we avoid +hitting the object database to parse these commits but instead only load +them from the commit-graph. This results in a significant performance +boost when executing git-fetch in said repository with 2.2 million refs: + + Benchmark #1: HEAD~: git fetch $remote $commit + Time (mean ± σ): 44.168 s ± 0.341 s [User: 42.985 s, System: 1.106 s] + Range (min … max): 43.565 s … 44.577 s 10 runs + + Benchmark #2: HEAD: git fetch $remote $commit + Time (mean ± σ): 19.498 s ± 0.724 s [User: 18.751 s, System: 0.690 s] + Range (min … max): 18.629 s … 20.454 s 10 runs + + Summary + 'HEAD: git fetch $remote $commit' ran + 2.27 ± 0.09 times faster than 'HEAD~: git fetch $remote $commit' + +Signed-off-by: Patrick Steinhardt <ps@pks.im> +--- + fetch-pack.c | 10 ++++++++-- + 1 file changed, 8 insertions(+), 2 deletions(-) + +diff --git a/fetch-pack.c b/fetch-pack.c +index b0c7be717c..0bf7ed7e47 100644 +--- a/fetch-pack.c ++++ b/fetch-pack.c +@@ -137,8 +137,14 @@ static struct commit *deref_without_lazy_fetch(const struct object_id *oid, + break; + } + } +- if (type == OBJ_COMMIT) +- return (struct commit *) parse_object(the_repository, oid); ++ ++ if (type == OBJ_COMMIT) { ++ struct commit *commit = lookup_commit(the_repository, oid); ++ if (!commit || repo_parse_commit(the_repository, commit)) ++ return NULL; ++ return commit; ++ } ++ + return NULL; + } + +-- +2.32.0 + |