Johannes Schindelin
e4621a0169
Since589127caa7(packfile: move list of packs into the packfile store, 2025-10-30), there is a performance regression when many packfiles need to be loaded: `packfile_store_add_pack()` now calls `packfile_list_remove_internal()` to detect whether the packfile was _already_ in the list, and if so, move it to the end of the list. This function linearly scans the existing list before every insertion. Newly loading N packs therefore has complexity O(N²). In one reported use case (https://github.com/microsoft/git/issues/970), N equals 37,815 and caused a slow-down of a simple `git rev-parse --short HEAD` (which is regularly executed as part of `GIT_PS1`) from 0.4s to 4.5s. Let's fix this by establishing a fast path for known-new packfiles. The keen reader will note that there is currently only a single, "known-new" caller of the `packfile_list_append()` function, and wonder why not simply remove this check whether the packfile already exists in the list? Originally, when above-mentioned commit introduced that logic, there was a second caller in `prepare_midx()`, which would have required that check, but that caller was removed in6aff1f25a0(packfile: always add packfiles to MRU when adding a pack, 2025-10-30). Still, the function is declared in a header file, and to avoid any problems with in-flight or downstream callers, it is safer to extend the signature to be explicit whether or not to skip that check. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> 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.adoc to get started, then see
Documentation/giteveryday.adoc for a useful minimum set of commands, and
Documentation/git-<commandname>.adoc 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.adoc
(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 and Documentation/CodingGuidelines).
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string translations (localization l10) should see po/README.md
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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