9639474b6d
Sometimes a bitmap traversal still has to walk some commits manually, because those commits aren't included in the bitmap packfile (e.g., due to a push or commit since the last full repack). If we're given an object filter, we don't pass it down to this traversal. It's not necessary for correctness because the bitmap code has its own filters to post-process the bitmap result (which it must, to filter out the objects that _are_ mentioned in the bitmapped packfile). And with blob filters, there was no performance reason to pass along those filters, either. The fill-in traversal could omit them from the result, but it wouldn't save us any time to do so, since we'd still have to walk each tree entry to see if it's a blob or not. But now that we support tree filters, there's opportunity for savings. A tree:depth=0 filter means we can avoid accessing trees entirely, since we know we won't them (or any of the subtrees or blobs they point to). The new test in p5310 shows this off (the "partial bitmap" state is one where HEAD~100 and its ancestors are all in a bitmapped pack, but HEAD~100..HEAD are not). Here are the results (run against linux.git): Test HEAD^ HEAD ------------------------------------------------------------------------------------------------- [...] 5310.16: rev-list with tree filter (partial bitmap) 0.19(0.17+0.02) 0.03(0.02+0.01) -84.2% The absolute number of savings isn't _huge_, but keep in mind that we only omitted 100 first-parent links (in the version of linux.git here, that's 894 actual commits). In a more pathological case, we might have a much larger proportion of non-bitmapped commits. I didn't bother creating such a case in the perf script because the setup is expensive, and this is plenty to show the savings as a percentage. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git - fast, scalable, distributed revision control system
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 version 2 (some parts of it are under different licenses, compatible with the GPLv2). It was originally written by Linus Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
Many Git online resources are accessible from https://git-scm.com/ including full documentation and Git related tools.
See Documentation/gittutorial.txt to get started, then see
Documentation/giteveryday.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).
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 (read Documentation/SubmittingPatches for instructions on patch submission). 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 https://lore.kernel.org/git/, http://marc.info/?l=git and other archival sites.
Issues which are security relevant should be disclosed privately to the Git Security mailing list git-security@googlegroups.com.
The maintainer frequently sends the "What's cooking" reports that list the current status of various development topics to the mailing list. The discussion following them give a good reference for project status, development direction and remaining tasks.
The name "git" was given by Linus Torvalds when he wrote the very first version. He described the tool as "the stupid content tracker" and the name as (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