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Derrick Stolee 45f4eeb291 pack-bitmap-write: relax unique revwalk condition The previous commits improved the bitmap computation process for very long, linear histories with many refs by removing quadratic growth in how many objects were walked. The strategy of computing "intermediate commits" using bitmasks for which refs can reach those commits partitioned the poset of reachable objects so each part could be walked exactly once. This was effective for linear histories. However, there was a (significant) drawback: wide histories with many refs had an explosion of memory costs to compute the commit bitmasks during the exploration that discovers these intermediate commits. Since these wide histories are unlikely to repeat walking objects, the benefit of walking objects multiple times was not expensive before. But now, the commit walk before computing bitmaps is incredibly expensive. In an effort to discover a happy medium, this change reduces the walk for intermediate commits to only the first-parent history. This focuses the walk on how the histories converge, which still has significant reduction in repeat object walks. It is still possible to create quadratic behavior in this version, but it is probably less likely in realistic data shapes. Here is some data taken on a fresh clone of the kernel: \| runtime (sec) \| peak heap (GB) \| \| \| \| \| from \| with \| from \| with \| \| scratch \| existing \| scratch \| existing \| -----------+---------+----------+---------+----------- original \| 64.044 \| 83.241 \| 2.088 \| 2.194 \| last patch \| 45.049 \| 37.624 \| 2.267 \| 2.334 \| this patch \| 88.478 \| 53.218 \| 2.157 \| 2.224 \| Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Signed-off-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>		2020-12-08 14:49:07 -08:00
.github	Merge branch 'js/ci-github-set-env'	2020-11-11 13:18:39 -08:00
Documentation	Fifth batch	2020-11-11 13:18:40 -08:00
block-sha1	…
builtin	pack-bitmap-write: ignore BITMAP_FLAG_REUSE	2020-12-08 14:48:17 -08:00
ci	…
compat	…
contrib	Merge branch 'sd/prompt-local-variable'	2020-11-11 13:18:38 -08:00
ewah	bitmap: implement bitmap_is_subset()	2020-12-08 14:48:16 -08:00
git-gui	…
gitk-git	…
gitweb	…
mergetools	…
negotiator	…
perl	Merge branch 'jk/perl-warning'	2020-11-09 14:06:25 -08:00
po	…
ppc	…
refs	…
sha1collisiondetection@855827c583	…
sha1dc	…
sha256	…
t	pack-bitmap-write: relax unique revwalk condition	2020-12-08 14:49:07 -08:00
templates	…
trace2	…
vcs-svn	…
xdiff	…
.cirrus.yml	…
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.editorconfig	…
.gitattributes	…
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CODE_OF_CONDUCT.md	…
COPYING	…
GIT-VERSION-GEN	Git 2.29.2	2020-10-29 14:24:09 -07:00
INSTALL	…
LGPL-2.1	…
Makefile	Merge branch 'jk/perl-warning'	2020-11-09 14:06:25 -08:00
README.md	…
RelNotes	Git 2.29.2	2020-10-29 14:24:09 -07:00
abspath.c	…
aclocal.m4	…
add-interactive.c	…
add-interactive.h	…
add-patch.c	Merge branch 'dl/checkout-p-merge-base'	2020-10-27 15:09:51 -07:00
advice.c	…
advice.h	…
alias.c	…
alias.h	…
alloc.c	…
alloc.h	…
apply.c	…
apply.h	…
archive-tar.c	…
archive-zip.c	…
archive.c	…
archive.h	…
attr.c	…
attr.h	…
banned.h	…
base85.c	…
bisect.c	bisect: clear flags in passed repository	2020-10-31 10:46:34 -07:00
bisect.h	…
blame.c	…
blame.h	…
blob.c	…
blob.h	…
bloom.c	…
bloom.h	…
branch.c	…
branch.h	…
builtin.h	…
bulk-checkin.c	…
bulk-checkin.h	…
bundle.c	…
bundle.h	…
cache-tree.c	…
cache-tree.h	…
cache.h	…
chdir-notify.c	…
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check-builtins.sh	…
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checkout.c	…
checkout.h	…
color.c	…
color.h	…
column.c	…
column.h	…
combine-diff.c	…
command-list.txt	…
commit-graph.c	Merge branch 'ds/commit-graph-merging-fix'	2020-11-02 13:17:39 -08:00
commit-graph.h	…
commit-reach.c	…
commit-reach.h	…
commit-slab-decl.h	…
commit-slab-impl.h	…
commit-slab.h	…
commit.c	commit: implement commit_list_contains()	2020-12-08 14:48:16 -08:00
commit.h	commit: implement commit_list_contains()	2020-12-08 14:48:16 -08:00
common-main.c	…
config.c	…
config.h	…
config.mak.dev	Merge branch 'jk/perl-warning'	2020-11-09 14:06:25 -08:00
config.mak.in	…
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configure.ac	…
connect.c	…
connect.h	…
connected.c	…
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copy.c	…
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csum-file.c	…
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date.c	…
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delta-islands.c	…
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delta.h	…
detect-compiler	…
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diff-lib.c	Merge branch 'nk/diff-files-vs-fsmonitor'	2020-11-09 14:06:25 -08:00
diff-no-index.c	…
diff.c	Merge branch 'mk/diff-ignore-regex'	2020-11-02 13:17:44 -08:00
diff.h	Merge branch 'mk/diff-ignore-regex'	2020-11-02 13:17:44 -08:00
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diffcore-pickaxe.c	…
diffcore-rename.c	…
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dir.c	Merge branch 'nk/dir-c-comment-update'	2020-11-02 13:17:42 -08:00
dir.h	…
editor.c	…
entry.c	…
environment.c	…
exec-cmd.c	…
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fetch-negotiator.c	…
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fmt-merge-msg.c	fmt-merge-msg: also suppress "into main" by default	2020-10-23 08:57:39 -07:00
fmt-merge-msg.h	…
fsck.c	…
fsck.h	…
fsmonitor.c	…
fsmonitor.h	…
fuzz-commit-graph.c	…
fuzz-pack-headers.c	…
fuzz-pack-idx.c	…
generate-cmdlist.sh	…
generate-configlist.sh	…
gettext.c	…
gettext.h	…
git-add--interactive.perl	Merge branch 'dl/checkout-p-merge-base'	2020-10-27 15:09:51 -07:00
git-archimport.perl	…
git-bisect.sh	Merge branch 'mr/bisect-in-c-3'	2020-11-09 14:06:25 -08:00
git-compat-util.h	Merge branch 'jk/report-fn-typedef'	2020-11-02 13:17:42 -08:00
git-cvsexportcommit.perl	…
git-cvsimport.perl	…
git-cvsserver.perl	…
git-difftool--helper.sh	…
git-filter-branch.sh	…
git-instaweb.sh	…
git-merge-octopus.sh	…
git-merge-one-file.sh	…
git-merge-resolve.sh	…
git-mergetool--lib.sh	…
git-mergetool.sh	…
git-p4.py	Merge branch 'js/p4-default-branch'	2020-11-11 13:18:38 -08:00
git-parse-remote.sh	…
git-quiltimport.sh	…
git-rebase--preserve-merges.sh	…
git-request-pull.sh	…
git-send-email.perl	…
git-sh-i18n.sh	…
git-sh-setup.sh	…
git-submodule.sh	…
git-svn.perl	…
git-web--browse.sh	…
git.c	…
git.rc	…
gpg-interface.c	…
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graph.c	…
graph.h	…
grep.c	…
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hash.h	…
hashmap.c	…
hashmap.h	…
help.c	…
help.h	…
hex.c	…
http-backend.c	…
http-fetch.c	…
http-push.c	…
http-walker.c	…
http.c	…
http.h	…
ident.c	…
imap-send.c	…
iterator.h	…
json-writer.c	…
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khash.h	…
kwset.c	…
kwset.h	…
levenshtein.c	…
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line-log.c	…
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line-range.c	…
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linear-assignment.c	…
linear-assignment.h	…
list-objects-filter-options.c	…
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list-objects-filter.c	…
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list-objects.c	…
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list.h	…
ll-merge.c	…
ll-merge.h	…
lockfile.c	…
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log-tree.c	…
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ls-refs.c	…
ls-refs.h	…
mailinfo.c	…
mailinfo.h	…
mailmap.c	…
mailmap.h	…
match-trees.c	…
mem-pool.c	…
mem-pool.h	…
merge-blobs.c	…
merge-blobs.h	…
merge-recursive.c	…
merge-recursive.h	…
merge.c	…
mergesort.c	…
mergesort.h	…
midx.c	Merge branch 'ds/maintenance-part-2'	2020-10-27 15:09:47 -07:00
midx.h	…
name-hash.c	…
notes-cache.c	…
notes-cache.h	…
notes-merge.c	…
notes-merge.h	…
notes-utils.c	…
notes-utils.h	…
notes.c	…
notes.h	…
object-store.h	…
object.c	object: allow clear_commit_marks_all to handle any repo	2020-10-31 10:46:34 -07:00
object.h	object: allow clear_commit_marks_all to handle any repo	2020-10-31 10:46:34 -07:00
oid-array.c	…
oid-array.h	…
oidmap.c	…
oidmap.h	…
oidset.c	…
oidset.h	…
pack-bitmap-write.c	pack-bitmap-write: relax unique revwalk condition	2020-12-08 14:49:07 -08:00
pack-bitmap.c	pack-bitmap: factor out 'add_commit_to_bitmap()'	2020-12-08 14:49:06 -08:00
pack-bitmap.h	pack-bitmap: factor out 'bitmap_for_commit()'	2020-12-08 14:49:04 -08:00
pack-check.c	…
pack-objects.c	…
pack-objects.h	…
pack-revindex.c	…
pack-revindex.h	…
pack-write.c	pack-write: use hashwrite_be32() instead of double-buffering array	2020-11-01 15:52:51 -08:00
pack.h	…
packfile.c	…
packfile.h	…
pager.c	…
parse-options-cb.c	…
parse-options.c	…
parse-options.h	…
patch-delta.c	…
patch-ids.c	…
patch-ids.h	…
path.c	…
path.h	…
pathspec.c	…
pathspec.h	…
pkt-line.c	sideband: diagnose more sideband anomalies	2020-10-29 09:23:29 -07:00
pkt-line.h	…
preload-index.c	…
pretty.c	…
pretty.h	…
prio-queue.c	…
prio-queue.h	…
progress.c	…
progress.h	…
promisor-remote.c	…
promisor-remote.h	…
prompt.c	…
prompt.h	…
protocol.c	…
protocol.h	…
prune-packed.c	…
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quote.c	…
quote.h	…
range-diff.c	…
range-diff.h	…
reachable.c	…
reachable.h	…
read-cache.c	…
rebase-interactive.c	…
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rebase.c	…
rebase.h	…
ref-filter.c	ref-filter: handle CRLF at end-of-line more gracefully	2020-10-29 12:57:45 -07:00
ref-filter.h	…
reflog-walk.c	…
reflog-walk.h	…
refs.c	tests: start moving to a different default main branch name	2020-10-23 08:57:40 -07:00
refs.h	…
refspec.c	Merge branch 'sb/clone-origin'	2020-10-27 15:09:50 -07:00
refspec.h	Merge branch 'sb/clone-origin'	2020-10-27 15:09:50 -07:00
remote-curl.c	…
remote.c	Merge branch 'sk/force-if-includes'	2020-10-27 15:09:49 -07:00
remote.h	Merge branch 'sk/force-if-includes'	2020-10-27 15:09:49 -07:00
replace-object.c	…
replace-object.h	…
repo-settings.c	Merge branch 'ds/maintenance-part-2'	2020-10-27 15:09:47 -07:00
repository.c	…
repository.h	Merge branch 'ds/maintenance-part-2'	2020-10-27 15:09:47 -07:00
rerere.c	…
rerere.h	…
reset.c	…
reset.h	…
resolve-undo.c	…
resolve-undo.h	…
revision.c	…
revision.h	…
run-command.c	…
run-command.h	…
send-pack.c	Merge branch 'sk/force-if-includes'	2020-10-27 15:09:49 -07:00
send-pack.h	…
sequencer.c	Merge branch 'jc/sequencer-stopped-sha-simplify'	2020-11-11 13:18:40 -08:00
sequencer.h	Merge branch 'jk/committer-date-is-author-date-fix-simplify'	2020-11-09 14:06:28 -08:00
serve.c	…
serve.h	…
server-info.c	…
setup.c	…
sh-i18n--envsubst.c	…
sha1-file.c	…
sha1-lookup.c	…
sha1-lookup.h	…
sha1-name.c	…
sha1dc_git.c	…
sha1dc_git.h	…
shallow.c	…
shallow.h	…
shell.c	…
shortlog.h	…
sideband.c	Merge branch 'jk/sideband-more-error-checking'	2020-11-09 14:06:29 -08:00
sideband.h	sideband: diagnose more sideband anomalies	2020-10-29 09:23:29 -07:00
sigchain.c	…
sigchain.h	…
split-index.c	…
split-index.h	…
stable-qsort.c	…
strbuf.c	…
strbuf.h	…
streaming.c	…
streaming.h	…
string-list.c	…
string-list.h	…
strvec.c	…
strvec.h	…
sub-process.c	…
sub-process.h	…
submodule-config.c	…
submodule-config.h	…
submodule.c	…
submodule.h	…
symlinks.c	…
tag.c	…
tag.h	…
tar.h	…
tempfile.c	…
tempfile.h	…
thread-utils.c	…
thread-utils.h	…
tmp-objdir.c	…
tmp-objdir.h	…
trace.c	…
trace.h	…
trace2.c	…
trace2.h	…
trailer.c	…
trailer.h	…
transport-helper.c	…
transport-internal.h	…
transport.c	…
transport.h	…
tree-diff.c	…
tree-walk.c	…
tree-walk.h	…
tree.c	…
tree.h	…
unicode-width.h	…
unimplemented.sh	…
unix-socket.c	…
unix-socket.h	…
unpack-trees.c	…
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upload-pack.c	…
upload-pack.h	…
url.c	…
url.h	…
urlmatch.c	…
urlmatch.h	…
usage.c	…
userdiff.c	Merge branch 've/userdiff-bash'	2020-11-02 13:17:46 -08:00
userdiff.h	…
utf8.c	…
utf8.h	…
varint.c	…
varint.h	…
version.c	…
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versioncmp.c	…
walker.c	…
walker.h	…
wildmatch.c	…
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worktree.c	…
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ws.c	…
wt-status.c	…
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xdiff-interface.h	…
zlib.c	…

README.md

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