From: Derrick Stolee <stolee@xxxxxxxxx> As custom options are added to 'git pack-objects' and 'git repack' to adjust how compression is done, use this new performance test script to demonstrate their effectiveness in performance and size. The recently-added --full-name-hash option swaps the default name-hash algorithm with one that attempts to uniformly distribute the hashes based on the full path name instead of the last 16 characters. This has a dramatic effect on full repacks for repositories with many versions of most paths. It can have a negative impact on cases such as pushing a single change. This can be seen by running pt5313 on the open source fluentui repository [1]. Most commits will have this kind of output for the thin and big pack cases, though certain commits (such as [2]) will have problematic thin pack size for other reasons. [1] https://github.com/microsoft/fluentui [2] a637a06df05360ce5ff21420803f64608226a875 Checked out at the parent of [2], I see the following statistics: Test this tree ------------------------------------------------------------------ 5313.2: thin pack 0.02(0.01+0.01) 5313.3: thin pack size 1.1K 5313.4: thin pack with --full-name-hash 0.02(0.01+0.00) 5313.5: thin pack size with --full-name-hash 3.0K 5313.6: big pack 1.65(3.35+0.24) 5313.7: big pack size 58.0M 5313.8: big pack with --full-name-hash 1.53(2.52+0.18) 5313.9: big pack size with --full-name-hash 57.6M 5313.10: repack 176.52(706.60+3.53) 5313.11: repack size 446.7K 5313.12: repack with --full-name-hash 37.47(134.18+3.06) 5313.13: repack size with --full-name-hash 183.1K Note that this demonstrates a 3x size _increase_ in the case that simulates a small "git push". The size change is neutral on the case of pushing the difference between HEAD and HEAD~1000. However, the full repack case is both faster and more efficient. Signed-off-by: Derrick Stolee <stolee@xxxxxxxxx> --- t/perf/p5313-pack-objects.sh | 71 ++++++++++++++++++++++++++++++++++++ 1 file changed, 71 insertions(+) create mode 100755 t/perf/p5313-pack-objects.sh diff --git a/t/perf/p5313-pack-objects.sh b/t/perf/p5313-pack-objects.sh new file mode 100755 index 00000000000..88ea0a4698a --- /dev/null +++ b/t/perf/p5313-pack-objects.sh @@ -0,0 +1,71 @@ +#!/bin/sh + +test_description='Tests pack performance using bitmaps' +. ./perf-lib.sh + +GIT_TEST_PASSING_SANITIZE_LEAK=0 +export GIT_TEST_PASSING_SANITIZE_LEAK + +test_perf_large_repo + +test_expect_success 'create rev input' ' + cat >in-thin <<-EOF && + $(git rev-parse HEAD) + ^$(git rev-parse HEAD~1) + EOF + + cat >in-big <<-EOF + $(git rev-parse HEAD) + ^$(git rev-parse HEAD~1000) + EOF +' + +test_perf 'thin pack' ' + git pack-objects --thin --stdout --revs --sparse <in-thin >out +' + +test_size 'thin pack size' ' + wc -c <out +' + +test_perf 'thin pack with --full-name-hash' ' + git pack-objects --thin --stdout --revs --sparse --full-name-hash <in-thin >out +' + +test_size 'thin pack size with --full-name-hash' ' + wc -c <out +' + +test_perf 'big pack' ' + git pack-objects --stdout --revs --sparse <in-big >out +' + +test_size 'big pack size' ' + wc -c <out +' + +test_perf 'big pack with --full-name-hash' ' + git pack-objects --stdout --revs --sparse --full-name-hash <in-big >out +' + +test_size 'big pack size with --full-name-hash' ' + wc -c <out +' + +test_perf 'repack' ' + git repack -adf +' + +test_size 'repack size' ' + du -a .git/objects/pack | sort -nr | awk "{ print \$1; }" | head -n 1 +' + +test_perf 'repack with --full-name-hash' ' + git repack -adf --full-name-hash +' + +test_size 'repack size with --full-name-hash' ' + du -a .git/objects/pack | sort -nr | awk "{ print \$1; }" | head -n 1 +' + +test_done -- gitgitgadget
