Implement a straightforward performance test demonstrating the benefit
of pseudo-merge bitmaps by measuring how long it takes to count
reachable objects in a few different scenarios:
- without bitmaps, to demonstrate a reasonable baseline
- with bitmaps, but without pseudo-merges
- with bitmaps and pseudo-merges
Results from running this test on git.git are as follows:
Test this tree
-----------------------------------------------------------------------------------
5333.2: git rev-list --count --all --objects (no bitmaps) 3.54(3.45+0.08)
5333.3: git rev-list --count --all --objects (no pseudo-merges) 0.43(0.40+0.03)
5333.4: git rev-list --count --all --objects (with pseudo-merges) 0.12(0.11+0.01)
On a private repository which is much larger, and has many spikey parts
of history that aren't merged into the 'master' branch, the results are
as follows:
Test this tree
---------------------------------------------------------------------------------------
5333.1: git rev-list --count --all --objects (no bitmaps) 122.29(121.31+0.97)
5333.2: git rev-list --count --all --objects (no pseudo-merges) 21.88(21.30+0.58)
5333.3: git rev-list --count --all --objects (with pseudo-merges) 5.05(4.77+0.28)
Signed-off-by: Taylor Blau <me@xxxxxxxxxxxx>
---
t/perf/p5333-pseudo-merge-bitmaps.sh | 32 ++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
create mode 100755 t/perf/p5333-pseudo-merge-bitmaps.sh
diff --git a/t/perf/p5333-pseudo-merge-bitmaps.sh b/t/perf/p5333-pseudo-merge-bitmaps.sh
new file mode 100755
index 00000000000..2e8b1d2635e
--- /dev/null
+++ b/t/perf/p5333-pseudo-merge-bitmaps.sh
@@ -0,0 +1,32 @@
+#!/bin/sh
+
+test_description='pseudo-merge bitmaps'
+. ./perf-lib.sh
+
+test_perf_large_repo
+
+test_expect_success 'setup' '
+ git \
+ -c bitmapPseudoMerge.all.pattern="refs/" \
+ -c bitmapPseudoMerge.all.threshold=now \
+ -c bitmapPseudoMerge.all.stableThreshold=never \
+ -c bitmapPseudoMerge.all.maxMerges=64 \
+ -c pack.writeBitmapLookupTable=true \
+ repack -adb
+'
+
+test_perf 'git rev-list --count --all --objects (no bitmaps)' '
+ git rev-list --objects --all
+'
+
+test_perf 'git rev-list --count --all --objects (no pseudo-merges)' '
+ GIT_TEST_USE_PSEUDO_MERGES=0 \
+ git rev-list --objects --all --use-bitmap-index
+'
+
+test_perf 'git rev-list --count --all --objects (with pseudo-merges)' '
+ GIT_TEST_USE_PSEUDO_MERGES=1 \
+ git rev-list --objects --all --use-bitmap-index
+'
+
+test_done
--
2.45.1.175.gcf0316ad0e9
