The low-level grep_source code will automatically load the
userdiff driver to see whether a file is binary. However,
when we are threaded, it will load the drivers in a
non-deterministic order, handling each one as its assigned
thread happens to be scheduled.
Meanwhile, the attribute lookup code (which underlies the
userdiff driver lookup) is optimized to handle paths in
sequential order (because they tend to share the same
gitattributes files). Multi-threading the lookups destroys
the locality and makes this optimization less effective.
We can fix this by pre-loading the userdiff driver in the
main thread, before we hand off the file to a worker thread.
My best-of-five for "git grep foo" on the linux-2.6
repository went from:
real 0m0.391s
user 0m1.708s
sys 0m0.584s
to:
real 0m0.360s
user 0m1.576s
sys 0m0.572s
Not a huge speedup, but it's quite easy to do. The only
trick is that we shouldn't perform this optimization if "-a"
was used, in which case we won't bother checking whether
the files are binary at all.
Signed-off-by: Jeff King <peff@peff.net>
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.
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