From: Junio C Hamano <gitster@pobox.com>
To: "Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, git@jeffhostetler.com, me@ttaylorr.com,
chakrabortyabhradeep79@gmail.com,
Derrick Stolee <derrickstolee@github.com>
Subject: Re: [PATCH] pack-bitmap: remove trace2 region from hot path
Date: Fri, 23 Sep 2022 10:36:44 -0700 [thread overview]
Message-ID: <xmqq7d1uuh5f.fsf@gitster.g> (raw)
In-Reply-To: <pull.1365.git.1663938034607.gitgitgadget@gmail.com> (Derrick Stolee via GitGitGadget's message of "Fri, 23 Sep 2022 13:00:34 +0000")
"Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com> writes:
> I noticed this while trying to backport the Abhradeep's lookup table
> work into GitHub's fork. Something went wrong in that process, causing
> this region to significantly slow down. It turns out that slow down does
> not reproduce on current 'master', which is good. I must have missed
> something while I was backporting.
>
> Regardless, the use of trace2_region_enter() here should be removed or
> replaced. For the sake of 2.38.0, this simple removal is safe enough.
Well, not doing this removal is even safer, if we know that it is
not hurting in the -rc code. It would be better than breaking our
tests without knowing ;-) I am not upset that the patch broke the
test, by the way. Compared to things silently breaking without
surfacing, a loud breakage in tests is a much easier thing to
handle.
My test run with the attached just finished, so that's what I am
going to queue tentatively on top.
Thanks.
pack-bitmap.c | 1 +
t/t5310-pack-bitmaps.sh | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git c/pack-bitmap.c w/pack-bitmap.c
index 13457dd77e..a2bbbbd811 100644
--- c/pack-bitmap.c
+++ w/pack-bitmap.c
@@ -830,6 +830,7 @@ struct ewah_bitmap *bitmap_for_commit(struct bitmap_index *bitmap_git,
if (!bitmap_git->table_lookup)
return NULL;
+ /* this is a fairly hot codepath - no trace2_region please */
/* NEEDSWORK: cache misses aren't recorded */
bitmap = lazy_bitmap_for_commit(bitmap_git, commit);
if (!bitmap)
diff --git c/t/t5310-pack-bitmaps.sh w/t/t5310-pack-bitmaps.sh
index 7e50f8e765..2b1efc923b 100755
--- c/t/t5310-pack-bitmaps.sh
+++ w/t/t5310-pack-bitmaps.sh
@@ -455,7 +455,7 @@ test_expect_success 'verify writing bitmap lookup table when enabled' '
grep "\"label\":\"writing_lookup_table\"" trace2
'
-test_expect_success 'lookup table is actually used to traverse objects' '
+: test_expect_success 'lookup table is actually used to traverse objects' '
git repack -adb &&
GIT_TRACE2_EVENT="$(pwd)/trace3" \
git rev-list --use-bitmap-index --count --all &&
next prev parent reply other threads:[~2022-09-23 17:39 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-23 13:00 [PATCH] pack-bitmap: remove trace2 region from hot path Derrick Stolee via GitGitGadget
2022-09-23 17:05 ` Junio C Hamano
2022-09-23 17:25 ` Junio C Hamano
2022-09-23 17:36 ` Junio C Hamano [this message]
2022-09-23 18:07 ` Derrick Stolee
2022-09-23 19:17 ` Taylor Blau
2022-09-26 13:17 ` [PATCH v2] " Derrick Stolee via GitGitGadget
2022-09-26 15:01 ` Ævar Arnfjörð Bjarmason
2022-09-26 17:31 ` Derrick Stolee
2022-09-27 18:37 ` [PATCH] " Jeff Hostetler
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