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Git performance tests ===================== This directory holds performance testing scripts for git tools. The first part of this document describes the various ways in which you can run them. When fixing the tools or adding enhancements, you are strongly encouraged to add tests in this directory to cover what you are trying to fix or enhance. The later part of this short document describes how your test scripts should be organized. Running Tests ------------- The easiest way to run tests is to say "make". This runs all the tests on the current git repository. === Running 2 tests in this tree === [...] Test this tree --------------------------------------------------------- 0001.1: rev-list --all 0.54(0.51+0.02) 0001.2: rev-list --all --objects 6.14(5.99+0.11) 7810.1: grep worktree, cheap regex 0.16(0.16+0.35) 7810.2: grep worktree, expensive regex 7.90(29.75+0.37) 7810.3: grep --cached, cheap regex 3.07(3.02+0.25) 7810.4: grep --cached, expensive regex 9.39(30.57+0.24) You can compare multiple repositories and even git revisions with the 'run' script: $ ./run . origin/next /path/to/git-tree p0001-rev-list.sh where . stands for the current git tree. The full invocation is ./run [<revision|directory>...] [--] [<test-script>...] A '.' argument is implied if you do not pass any other revisions/directories. You can also manually test this or another git build tree, and then call the aggregation script to summarize the results: $ ./p0001-rev-list.sh [...] $ GIT_BUILD_DIR=/path/to/other/git ./p0001-rev-list.sh [...] $ ./aggregate.perl . /path/to/other/git ./p0001-rev-list.sh aggregate.perl has the same invocation as 'run', it just does not run anything beforehand. You can set the following variables (also in your config.mak): GIT_PERF_REPEAT_COUNT Number of times a test should be repeated for best-of-N measurements. Defaults to 5. GIT_PERF_MAKE_OPTS Options to use when automatically building a git tree for performance testing. E.g., -j6 would be useful. GIT_PERF_REPO GIT_PERF_LARGE_REPO Repositories to copy for the performance tests. The normal repo should be at least git.git size. The large repo should probably be about linux-2.6.git size for optimal results. Both default to the git.git you are running from. You can also pass the options taken by ordinary git tests; the most useful one is: --root=<directory>:: Create "trash" directories used to store all temporary data during testing under <directory>, instead of the t/ directory. Using this option with a RAM-based filesystem (such as tmpfs) can massively speed up the test suite. Naming Tests ------------ The performance test files are named as: pNNNN-commandname-details.sh where N is a decimal digit. The same conventions for choosing NNNN as for normal tests apply. Writing Tests ------------- The perf script starts much like a normal test script, except it sources perf-lib.sh: #!/bin/sh # # Copyright (c) 2005 Junio C Hamano # test_description='xxx performance test' . ./perf-lib.sh After that you will want to use some of the following: test_perf_default_repo # sets up a "normal" repository test_perf_large_repo # sets up a "large" repository test_perf_default_repo sub # ditto, in a subdir "sub" test_checkout_worktree # if you need the worktree too At least one of the first two is required! You can use test_expect_success as usual. For actual performance tests, use test_perf 'descriptive string' ' command1 && command2 ' test_perf spawns a subshell, for lack of better options. This means that * you _must_ export all variables that you need in the subshell * you _must_ flag all variables that you want to persist from the subshell with 'test_export': test_perf 'descriptive string' ' foo=$(git rev-parse HEAD) && test_export foo ' The so-exported variables are automatically marked for export in the shell executing the perf test. For your convenience, test_export is the same as export in the main shell. This feature relies on a bit of magic using 'set' and 'source'. While we have tried to make sure that it can cope with embedded whitespace and other special characters, it will not work with multi-line data.