1bb10d4f7c
We don't cover the partial clone feature at all in t/perf. Let's at
least run a few basic tests so that we'll notice any regressions.
We'll do a no-blob clone, and split it into two parts: the actual object
transfer, and the subsequent checkout (which will of course require
another transfer to get the blobs). That will help us more clearly
assess the performance of each.
There are obviously a lot more possibilities besides just a no-blob
partial clone, but this should serve as a canary that alerts us to any
generic slow-downs (and we can add more tests later for cases that
aren't exercised here).
There are a few non-ideal things here that make this not an entirely
accurate test, but are probably OK for our purposes:
1. We have to do some extra prep/cleanup work inside the timing tests,
since they impact the on-disk state and the perf harness may run
each one multiple times.
In practice this is probably OK, since these bits should be much
less expensive than the operations we are measuring.
2. The clone time is likely to be dominated by the server's object
enumeration. In the real world, a repo large enough to drive people
to partial clones is likely to have reachability bitmaps enabled.
And in the opposite direction, our object transfer is happening at
the speed of a local pipe, whereas in the real world it would
bottle-neck on the network.
So any percentage speedups should be taken with a grain of salt.
But hopefully any regressions will produce enough of an effect to
be noticeable.
This script also demonstrates the recent improvement from dfa33a298d
(clone: do faster object check for partial clones, 2019-04-19):
Test dfa33a298d^ dfa33a298d
-------------------------------------------------------------------------
5600.2: clone without blobs 18.41(22.72+1.09) 6.83(11.65+0.50) -62.9%
5600.3: checkout of result 1.82(3.24+0.26) 1.84(3.24+0.26) +1.1%
Signed-off-by: Jeff King <peff@peff.net>
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-.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://public-inbox.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