9eceddeec6
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>
////////////////////////////////////////////////////////////////
GIT - the stupid content tracker
////////////////////////////////////////////////////////////////
"git" can mean anything, depending on your mood.
- random three-letter combination that is pronounceable, and not
actually used by any common UNIX command. The fact that it is a
mispronunciation of "get" may or may not be relevant.
- stupid. contemptible and despicable. simple. Take your pick from the
dictionary of slang.
- "global information tracker": you're in a good mood, and it actually
works for you. Angels sing, and a light suddenly fills the room.
- "goddamn idiotic truckload of sh*t": when it breaks
Git is a fast, scalable, distributed revision control system with an
unusually rich command set that provides both high-level operations
and full access to internals.
Git is an Open Source project covered by the GNU General Public License.
It was originally written by Linus Torvalds with help of a group of
hackers around the net. It is currently maintained by Junio C Hamano.
Please read the file INSTALL for installation instructions.
See Documentation/gittutorial.txt to get started, then see
Documentation/everyday.txt for a useful minimum set of commands, and
Documentation/git-commandname.txt for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with "man gittutorial" or "git help tutorial", and the
documentation of each command with "man git-commandname" or "git help
commandname".
CVS users may also want to read Documentation/gitcvs-migration.txt
("man gitcvs-migration" or "git help cvs-migration" if git is
installed).
Many Git online resources are accessible from http://git-scm.com/
including full documentation and Git related tools.
The user discussion and development of Git take place on the Git
mailing list -- everyone is welcome to post bug reports, feature
requests, comments and patches to git@vger.kernel.org. To subscribe
to the list, send an email with just "subscribe git" in the body to
majordomo@vger.kernel.org. The mailing list archives are available at
http://marc.theaimsgroup.com/?l=git and other archival sites.
The messages titled "A note from the maintainer", "What's in
git.git (stable)" and "What's cooking in git.git (topics)" and
the discussion following them on the mailing list give a good
reference for project status, development direction and
remaining tasks.