1 Git performance tests
2 =====================
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.
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.
14 Running Tests
15 -------------
17 The easiest way to run tests is to say "make". This runs all
18 the tests on the current git repository.
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)
31 You can compare multiple repositories and even git revisions with the
32 'run' script:
34 $ ./run . origin/next /path/to/git-tree p0001-rev-list.sh
36 where . stands for the current git tree. The full invocation is
38 ./run [<revision|directory>...] [--] [<test-script>...]
40 A '.' argument is implied if you do not pass any other
41 revisions/directories.
43 You can also manually test this or another git build tree, and then
44 call the aggregation script to summarize the results:
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
52 aggregate.perl has the same invocation as 'run', it just does not run
53 anything beforehand.
55 You can set the following variables (also in your config.mak):
57 GIT_PERF_REPEAT_COUNT
58 Number of times a test should be repeated for best-of-N
59 measurements. Defaults to 5.
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.
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.
72 You can also pass the options taken by ordinary git tests; the most
73 useful one is:
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.
82 Naming Tests
83 ------------
85 The performance test files are named as:
87 pNNNN-commandname-details.sh
89 where N is a decimal digit. The same conventions for choosing NNNN as
90 for normal tests apply.
93 Writing Tests
94 -------------
96 The perf script starts much like a normal test script, except it
97 sources perf-lib.sh:
99 #!/bin/sh
100 #
101 # Copyright (c) 2005 Junio C Hamano
102 #
104 test_description='xxx performance test'
105 . ./perf-lib.sh
107 After that you will want to use some of the following:
109 test_perf_default_repo # sets up a "normal" repository
110 test_perf_large_repo # sets up a "large" repository
112 test_perf_default_repo sub # ditto, in a subdir "sub"
114 test_checkout_worktree # if you need the worktree too
116 At least one of the first two is required!
118 You can use test_expect_success as usual. For actual performance
119 tests, use
121 test_perf 'descriptive string' '
122 command1 &&
123 command2
124 '
126 test_perf spawns a subshell, for lack of better options. This means
127 that
129 * you _must_ export all variables that you need in the subshell
131 * you _must_ flag all variables that you want to persist from the
132 subshell with 'test_export':
134 test_perf 'descriptive string' '
135 foo=$(git rev-parse HEAD) &&
136 test_export foo
137 '
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.
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.