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Add a performance comparison test of grep regex engines given fixed
strings.
The current logic in compile_regexp() ignores the engine parameter and
uses kwset() to search for these, so this test shows no difference
between engines right now:
$ GIT_PERF_REPEAT_COUNT=10 GIT_PERF_LARGE_REPO=~/g/linux ./run p7821-grep-engines-fixed.sh
[...]
Test this tree
------------------------------------------------
7821.1: fixed grep int 0.56(1.67+0.68)
7821.2: basic grep int 0.57(1.70+0.57)
7821.3: extended grep int 0.59(1.76+0.51)
7821.4: perl grep int 1.08(1.71+0.55)
7821.6: fixed grep uncommon 0.23(0.55+0.50)
7821.7: basic grep uncommon 0.24(0.55+0.50)
7821.8: extended grep uncommon 0.26(0.55+0.52)
7821.9: perl grep uncommon 0.24(0.58+0.47)
7821.11: fixed grep æ 0.36(1.30+0.42)
7821.12: basic grep æ 0.36(1.32+0.40)
7821.13: extended grep æ 0.38(1.30+0.42)
7821.14: perl grep æ 0.35(1.24+0.48)
Only when run with -i via GIT_PERF_7821_GREP_OPTS=' -i' do we avoid
avoid going through the same kwset.[ch] codepath, see the "Even when
-F..." comment in grep.c. This only kicks for the non-ASCII case:
$ GIT_PERF_REPEAT_COUNT=10 GIT_PERF_LARGE_REPO=~/g/linux GIT_PERF_7821_GREP_OPTS=' -i' ./run p7821-grep-engines-fixed.sh
[...]
Test this tree
---------------------------------------------------
7821.1: fixed grep -i int 0.62(2.10+0.57)
7821.2: basic grep -i int 0.68(1.90+0.61)
7821.3: extended grep -i int 0.78(1.94+0.57)
7821.4: perl grep -i int 0.98(1.78+0.74)
7821.6: fixed grep -i uncommon 0.24(0.44+0.64)
7821.7: basic grep -i uncommon 0.25(0.56+0.54)
7821.8: extended grep -i uncommon 0.27(0.62+0.45)
7821.9: perl grep -i uncommon 0.24(0.59+0.49)
7821.11: fixed grep -i æ 0.30(0.96+0.39)
7821.12: basic grep -i æ 0.27(0.92+0.44)
7821.13: extended grep -i æ 0.28(0.90+0.46)
7821.14: perl grep -i æ 0.28(0.74+0.49)
I'm planning to change how fixed-string searching happens. This test
gives a baseline for comparing performance before & after any such
change.
See commit ("perf: add a comparison test of grep regex engines",
2017-04-19) for details on the machine the above test run was executed
on.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Ævar Arnfjörð Bjarmason