[PATCH v2 1/2] t/perf: time rev-list with UNINTERESTING commits

From: Jeff King <peff@peff.net>
Date: Jan 21, 2014, 02:25 UTC
Message-ID: <20140121022511.GA4672@sigill.intra.peff.net>
In-Reply-To: <20140121022431.GA4614@sigill.intra.peff.net>

We time a straight "rev-list --all" and its "--object" counterpart, both going all the way to the root. However, we do not time a partial history walk. This patch adds an extreme case: a walk over a very small slice of history, but with a very large set of UNINTERESTING tips. This is similar to the connectivity check run by git on a small fetch, or the walk done by any pre-receive hooks that want to check incoming commits.

This test reveals a performance regression in git v1.8.4.2, caused by fbd4a70 (list-objects: mark more commits as edges in mark_edges_uninteresting, 2013-08-16):

Test fbd4a703^ fbd4a703 ------------------------------------------------------------------------------------------ 0001.1: rev-list --all 0.69(0.67+0.02) 0.69(0.68+0.01) +0.0% 0001.2: rev-list --all --objects 3.47(3.44+0.02) 3.48(3.44+0.03) +0.3% 0001.4: rev-list $commit --not --all 0.04(0.04+0.00) 0.04(0.04+0.00) +0.0% 0001.5: rev-list --objects $commit --not --all 0.04(0.03+0.00) 0.27(0.24+0.02) +575.0%

Signed-off-by: Jeff King <peff@peff.net>
---
 t/perf/p0001-rev-list.sh | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/t/perf/p0001-rev-list.sh b/t/perf/p0001-rev-list.sh
index 4f71a63..16359d5 100755
--- a/t/perf/p0001-rev-list.sh
+++ b/t/perf/p0001-rev-list.sh
@@ -14,4 +14,16 @@ test_perf 'rev-list --all --objects' '
 	git rev-list --all --objects >/dev/null
 '
 
+test_expect_success 'create new unreferenced commit' '
+	commit=$(git commit-tree HEAD^{tree} -p HEAD)
+'
+
+test_perf 'rev-list $commit --not --all' '
+	git rev-list $commit --not --all >/dev/null
+'
+
+test_perf 'rev-list --objects $commit --not --all' '
+	git rev-list --objects $commit --not --all >/dev/null
+'
+
 test_done

-- 
1.8.5.2.500.g8060133