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1 | Git performance tests |
| 2 | ===================== | |
| 3 | ||
| 4 | This directory holds performance testing scripts for git tools. The | |
| 5 | first part of this document describes the various ways in which you | |
| 6 | can run them. | |
| 7 | ||
| 8 | When fixing the tools or adding enhancements, you are strongly | |
| 9 | encouraged to add tests in this directory to cover what you are | |
| 10 | trying to fix or enhance. The later part of this short document | |
| 11 | describes how your test scripts should be organized. | |
| 12 | ||
| 13 | ||
| 14 | Running Tests | |
| 15 | ------------- | |
| 16 | ||
| 17 | The easiest way to run tests is to say "make". This runs all | |
| 18 | the tests on the current git repository. | |
| 19 | ||
| 20 | === Running 2 tests in this tree === | |
| 21 | [...] | |
| 22 | Test this tree | |
| 23 | --------------------------------------------------------- | |
| 24 | 0001.1: rev-list --all 0.54(0.51+0.02) | |
| 25 | 0001.2: rev-list --all --objects 6.14(5.99+0.11) | |
| 26 | 7810.1: grep worktree, cheap regex 0.16(0.16+0.35) | |
| 27 | 7810.2: grep worktree, expensive regex 7.90(29.75+0.37) | |
| 28 | 7810.3: grep --cached, cheap regex 3.07(3.02+0.25) | |
| 29 | 7810.4: grep --cached, expensive regex 9.39(30.57+0.24) | |
| 30 | ||
| 31 | You can compare multiple repositories and even git revisions with the | |
| 32 | 'run' script: | |
| 33 | ||
| 34 | $ ./run . origin/next /path/to/git-tree p0001-rev-list.sh | |
| 35 | ||
| 36 | where . stands for the current git tree. The full invocation is | |
| 37 | ||
| 38 | ./run [<revision|directory>...] [--] [<test-script>...] | |
| 39 | ||
| 40 | A '.' argument is implied if you do not pass any other | |
| 41 | revisions/directories. | |
| 42 | ||
| 43 | You can also manually test this or another git build tree, and then | |
| 44 | call the aggregation script to summarize the results: | |
| 45 | ||
| 46 | $ ./p0001-rev-list.sh | |
| 47 | [...] | |
| 48 | $ GIT_BUILD_DIR=/path/to/other/git ./p0001-rev-list.sh | |
| 49 | [...] | |
| 50 | $ ./aggregate.perl . /path/to/other/git ./p0001-rev-list.sh | |
| 51 | ||
| 52 | aggregate.perl has the same invocation as 'run', it just does not run | |
| 53 | anything beforehand. | |
| 54 | ||
| 55 | You can set the following variables (also in your config.mak): | |
| 56 | ||
| 57 | GIT_PERF_REPEAT_COUNT | |
| 58 | Number of times a test should be repeated for best-of-N | |
| 59 | measurements. Defaults to 5. | |
| 60 | ||
| 61 | GIT_PERF_MAKE_OPTS | |
| 62 | Options to use when automatically building a git tree for | |
| 63 | performance testing. E.g., -j6 would be useful. | |
| 64 | ||
| 65 | GIT_PERF_REPO | |
| 66 | GIT_PERF_LARGE_REPO | |
| 67 | Repositories to copy for the performance tests. The normal | |
| 68 | repo should be at least git.git size. The large repo should | |
| 69 | probably be about linux-2.6.git size for optimal results. | |
| 70 | Both default to the git.git you are running from. | |
| 71 | ||
| 72 | You can also pass the options taken by ordinary git tests; the most | |
| 73 | useful one is: | |
| 74 | ||
| 75 | --root=<directory>:: | |
| 76 | Create "trash" directories used to store all temporary data during | |
| 77 | testing under <directory>, instead of the t/ directory. | |
| 78 | Using this option with a RAM-based filesystem (such as tmpfs) | |
| 79 | can massively speed up the test suite. | |
| 80 | ||
| 81 | ||
| 82 | Naming Tests | |
| 83 | ------------ | |
| 84 | ||
| 85 | The performance test files are named as: | |
| 86 | ||
| 87 | pNNNN-commandname-details.sh | |
| 88 | ||
| 89 | where N is a decimal digit. The same conventions for choosing NNNN as | |
| 90 | for normal tests apply. | |
| 91 | ||
| 92 | ||
| 93 | Writing Tests | |
| 94 | ------------- | |
| 95 | ||
| 96 | The perf script starts much like a normal test script, except it | |
| 97 | sources perf-lib.sh: | |
| 98 | ||
| 99 | #!/bin/sh | |
| 100 | # | |
| 101 | # Copyright (c) 2005 Junio C Hamano | |
| 102 | # | |
| 103 | ||
| 104 | test_description='xxx performance test' | |
| 105 | . ./perf-lib.sh | |
| 106 | ||
| 107 | After that you will want to use some of the following: | |
| 108 | ||
| 109 | test_perf_default_repo # sets up a "normal" repository | |
| 110 | test_perf_large_repo # sets up a "large" repository | |
| 111 | ||
| 112 | test_perf_default_repo sub # ditto, in a subdir "sub" | |
| 113 | ||
| 114 | test_checkout_worktree # if you need the worktree too | |
| 115 | ||
| 116 | At least one of the first two is required! | |
| 117 | ||
| 118 | You can use test_expect_success as usual. For actual performance | |
| 119 | tests, use | |
| 120 | ||
| 121 | test_perf 'descriptive string' ' | |
| 122 | command1 && | |
| 123 | command2 | |
| 124 | ' | |
| 125 | ||
| 126 | test_perf spawns a subshell, for lack of better options. This means | |
| 127 | that | |
| 128 | ||
| 129 | * you _must_ export all variables that you need in the subshell | |
| 130 | ||
| 131 | * you _must_ flag all variables that you want to persist from the | |
| 132 | subshell with 'test_export': | |
| 133 | ||
| 134 | test_perf 'descriptive string' ' | |
| 135 | foo=$(git rev-parse HEAD) && | |
| 136 | test_export foo | |
| 137 | ' | |
| 138 | ||
| 139 | The so-exported variables are automatically marked for export in the | |
| 140 | shell executing the perf test. For your convenience, test_export is | |
| 141 | the same as export in the main shell. | |
| 142 | ||
| 143 | This feature relies on a bit of magic using 'set' and 'source'. | |
| 144 | While we have tried to make sure that it can cope with embedded | |
| 145 | whitespace and other special characters, it will not work with | |
| 146 | multi-line data. |