Use kwset in grep
Benchmarks for the hot cache case:
before:
$ perf stat --repeat=5 git grep qwerty > /dev/null
Performance counter stats for 'git grep qwerty' (5 runs):
3,478,085 cache-misses # 2.322 M/sec ( +- 2.690% )
11,356,177 cache-references # 7.582 M/sec ( +- 2.598% )
3,872,184 branch-misses # 0.363 % ( +- 0.258% )
1,067,367,848 branches # 712.673 M/sec ( +- 2.622% )
3,828,370,782 instructions # 0.947 IPC ( +- 0.033% )
4,043,832,831 cycles # 2700.037 M/sec ( +- 0.167% )
8,518 page-faults # 0.006 M/sec ( +- 3.648% )
847 CPU-migrations # 0.001 M/sec ( +- 3.262% )
6,546 context-switches # 0.004 M/sec ( +- 2.292% )
1497.695495 task-clock-msecs # 3.303 CPUs ( +- 2.550% )
0.
453394396 seconds time elapsed ( +- 0.912% )
after:
$ perf stat --repeat=5 git grep qwerty > /dev/null
Performance counter stats for 'git grep qwerty' (5 runs):
2,989,918 cache-misses # 3.166 M/sec ( +- 5.013% )
10,986,041 cache-references # 11.633 M/sec ( +- 4.899% ) (scaled from 95.06%)
3,511,993 branch-misses # 1.422 % ( +- 0.785% )
246,893,561 branches # 261.433 M/sec ( +- 3.967% )
1,392,727,757 instructions # 0.564 IPC ( +- 0.040% )
2,468,142,397 cycles # 2613.494 M/sec ( +- 0.110% )
7,747 page-faults # 0.008 M/sec ( +- 3.995% )
897 CPU-migrations # 0.001 M/sec ( +- 2.383% )
6,535 context-switches # 0.007 M/sec ( +- 1.993% )
944.384228 task-clock-msecs # 3.177 CPUs ( +- 0.268% )
0.
297257643 seconds time elapsed ( +- 0.450% )
So we gain about 35% by using the kwset code.
As a side effect of using kwset two grep tests are fixed by this
patch. The first is fixed because kwset can deal with case-insensitive
search containing NULs, something strcasestr cannot do. The second one
is fixed because we consider patterns containing NULs as fixed strings
(regcomp cannot accept patterns with NULs).
Signed-off-by: Fredrik Kuivinen <frekui@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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