"Derrick Stolee via GitGitGadget" <gitgitgadget@xxxxxxxxx> writes: > 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. Nice. > 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 "wc -c" -> "test_file_size" or "test-tool path-utils file-size"?
