From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.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>,
"Junio C Hamano" <gitster@pobox.com>
Subject: Re: [PATCH v2 1/3] p5400: add perf tests for git-receive-pack(1)
Date: Tue, 29 Jun 2021 14:09:25 +0200 [thread overview]
Message-ID: <87r1gkg8rf.fsf@evledraar.gmail.com> (raw)
In-Reply-To: <YNq7MD/fMQp05I21@ncase>
On Tue, Jun 29 2021, Patrick Steinhardt wrote:
> [[PGP Signed Part:Undecided]]
> On Mon, Jun 28, 2021 at 09:49:54AM +0200, Ævar Arnfjörð Bjarmason wrote:
>>
>> On Mon, Jun 28 2021, Patrick Steinhardt wrote:
>>
>> > [[PGP Signed Part:Undecided]]
>> > We'll the connectivity check logic for git-receive-pack(1) in the
>> > following commits to make it perform better. As a preparatory step, add
>> > some benchmarks such that we can measure these changes.
>> >
>> > Signed-off-by: Patrick Steinhardt <ps@pks.im>
>> > ---
>> > t/perf/p5400-receive-pack.sh | 97 ++++++++++++++++++++++++++++++++++++
>> > 1 file changed, 97 insertions(+)
>> > create mode 100755 t/perf/p5400-receive-pack.sh
>> >
>> > diff --git a/t/perf/p5400-receive-pack.sh b/t/perf/p5400-receive-pack.sh
>> > new file mode 100755
>> > index 0000000000..a945e014a3
>> > --- /dev/null
>> > +++ b/t/perf/p5400-receive-pack.sh
>> > @@ -0,0 +1,97 @@
>> > +#!/bin/sh
>> > +
>> > +test_description="Tests performance of receive-pack"
>> > +
>> > +. ./perf-lib.sh
>> > +
>> > +test_perf_large_repo
>>
>> From the runtime I think this just needs test_perf_default_repo, no?
>> I.e. we should only have *_large_* for cases where git.git is too small
>> to produce meaningful results.
>>
>> Part of th problem is that git.git has become larger over time...
>
> I did these tests for 3/3 with git.git first, and results were
> significantly different. The performance issues I'm trying to fix with
> the connectivity check really only start to show up with largish
> repositories.
>
>> > +test_expect_success 'setup' '
>> > + # Create a main branch such that we do not have to rely on any specific
>> > + # branch to exist in the perf repository.
>> > + git switch --force-create main &&
>> > +
>> > + # Set up a pre-receive hook such that no refs will ever be changed.
>> > + # This easily allows multiple perf runs, but still exercises
>> > + # server-side reference negotiation and checking for consistency.
>> > + mkdir hooks &&
>> > + write_script hooks/pre-receive <<-EOF &&
>> > + #!/bin/sh
>>
>> You don't need the #!/bin/sh here, and it won't be used. write_script()
>> adds it (or the wanted shell path).
>
> Makes sense.
>
>> > + echo "failed in pre-receive hook"
>> > + exit 1
>> > + EOF
>> > + cat >config <<-EOF &&
>> > + [core]
>> > + hooksPath=$(pwd)/hooks
>> > + EOF
>>
>> Easier understood IMO as:
>>
>> git config -f config core.hooksPath ...
>
> Yup, will change.
>
>> > + GIT_CONFIG_GLOBAL="$(pwd)/config" &&
>> > + export GIT_CONFIG_GLOBAL &&
>> > +
>> > + git switch --create updated &&
>> > + test_commit --no-tag updated
>> > +'
>> > +
>> > +setup_empty() {
>> > + git init --bare "$2"
>> > +}
>>
>> I searched ahead for setup_empty, looked unused, but...
>>
>> > +setup_clone() {
>> > + git clone --bare --no-local --branch main "$1" "$2"
>> > +}
>> > +
>> > +setup_clone_bitmap() {
>> > + git clone --bare --no-local --branch main "$1" "$2" &&
>> > + git -C "$2" repack -Adb
>> > +}
>> > +
>> > +# Create a reference for each commit in the target repository with extra-refs.
>> > +# While this may be an atypical setup, biggish repositories easily end up with
>> > +# hundreds of thousands of refs, and this is a good enough approximation.
>> > +setup_extrarefs() {
>> > + git clone --bare --no-local --branch main "$1" "$2" &&
>> > + git -C "$2" log --all --format="tformat:create refs/commit/%h %H" |
>> > + git -C "$2" update-ref --stdin
>> > +}
>> > +
>> > +# Create a reference for each commit in the target repository with extra-refs.
>> > +# While this may be an atypical setup, biggish repositories easily end up with
>> > +# hundreds of thousands of refs, and this is a good enough approximation.
>> > +setup_extrarefs_bitmap() {
>> > + git clone --bare --no-local --branch main "$1" "$2" &&
>> > + git -C "$2" log --all --format="tformat:create refs/commit/%h %H" |
>> > + git -C "$2" update-ref --stdin &&
>> > + git -C "$2" repack -Adb
>> > +}
>> > +
>> > +for repo in empty clone clone_bitmap extrarefs extrarefs_bitmap
>> > +do
>> > + test_expect_success "$repo setup" '
>>
>> > + rm -rf target.git &&
>> > + setup_$repo "$(pwd)" target.git
>>
>> ...here we use it via interpolation.
>>
>> I'd find this whole pattern much easier to understand if the setups were
>> just a bunch of test_expect_success that created a repo_empty.git,
>> repo_extrarefs.git etc. Then this loop would be:
>>
>> for repo in repo*.git ...
>>
>> I'd think that would also give you more meaningful perf data, as now the
>> OS will churn between the clone & the subsequent push tests, better to
>> do all the setup, then all the different perf tests.
>>
>> Perhaps there's also a way to re-use this setup across different runs, I
>> don't know/can't remember if t/perf has a less transient thing than the
>> normal trash directory to use for that.
>
> I originally had code like this, but the issue with first creating all
> the repos is that it requires lots of disk space with large repos given
> that we'll clone it once per setup. Combined with the fact that I
> often run tests in tmpfs, this led to out-of-memory situations quite
> fast given that I had 3x6GB repositories plus the seeded packfiles in
> RAM.
>
> This is why I've changed the setup to do the setup as we go, to bring
> disk usage down to something sane.
>
> Patrick
>
> [[End of PGP Signed Part]]
Ah, I see. In that case wouldn't it be even better/faster with/without
my suggestion to not use "clone" here, which would either be manually
set up with alternates, or removing the --no-local flag.
You'd then share bulk of the object database, and just have different
references. B.t.w. you'll probably get less noise/more relevant results
if you then do a "pack-refs" after creating those N references.
So you should have:
0. Your "big" test repop (not used directly)
1. An empty repo
2. The "big" test repo itself, but just the HEAD branch, using
alternates to point to #0
3. Ditto, but we create a crapload of refs for each commit for a
version of #2.
4. Ditto #3 (could even "cp" over the packed refs file to save time),
but add a bitmap on top.
Well, presumably for #4 we'd actually want to do the "git repack -Adb"
for #2 (or enforce that #0 must have it), then just move the *.bitmap
file(s) to #4. Now the test case conflates whether we have bitmaps with
how well (re)packed something is.
I think this might also allow you to get rid of the pre-receive hook for
a "real" push test, since the side-repos would be so cheap at this point
that you could perhaps setup N of them to push into.
next prev parent reply other threads:[~2021-06-29 12:23 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 [this message]
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
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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