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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
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
You can also manually test this or another git build tree, and then
call the aggregation script to summarize the results:
$ ./
$ GIT_BUILD_DIR=/path/to/other/git ./
$ ./aggregate.perl . /path/to/other/git ./
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):
Number of times a test should be repeated for best-of-N
measurements. Defaults to 5.
Options to use when automatically building a git tree for
performance testing. E.g., -j6 would be useful.
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:
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:
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
# Copyright (c) 2005 Junio C Hamano
test_description='xxx performance test'
. ./
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 &&
test_perf spawns a subshell, for lack of better options. This means
* 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.