Commit Graph

80 Commits

Author SHA1 Message Date
Junio C Hamano
6cbc478d83 Merge branch 'jh/add-index-entry-optim'
"git checkout" that handles a lot of paths has been optimized by
reducing the number of unnecessary checks of paths in the
has_dir_name() function.

* jh/add-index-entry-optim:
  read-cache: speed up has_dir_name (part 2)
  read-cache: speed up has_dir_name (part 1)
  read-cache: speed up add_index_entry during checkout
  p0006-read-tree-checkout: perf test to time read-tree
  read-cache: add strcmp_offset function
2017-04-26 15:39:07 +09:00
Junio C Hamano
8b6bba6663 Merge branch 'jh/string-list-micro-optim'
The string-list API used a custom reallocation strategy that was
very inefficient, instead of using the usual ALLOC_GROW() macro,
which has been fixed.

* jh/string-list-micro-optim:
  string-list: use ALLOC_GROW macro when reallocing string_list
2017-04-23 22:07:47 -07:00
Junio C Hamano
8377f34540 Merge branch 'jh/memihash-opt'
Hotfix for a topic that is already in 'master'.

* jh/memihash-opt:
  p0004: make perf test executable
  t3008: skip lazy-init test on a single-core box
  test-online-cpus: helper to return cpu count
  name-hash: fix buffer overrun
2017-04-19 21:37:25 -07:00
Jeff Hostetler
350d870143 p0006-read-tree-checkout: perf test to time read-tree
Created t/perf/repos/many-files.sh to generate large, but
artificial repositories.

Created t/perf/inflate-repo.sh to alter an EXISTING repo
to have a set of large commits.  This can be used to create
a branch with 1M+ files in repositories like git.git or
linux.git, but with more realistic content.  It does this
by making multiple copies of the entire worktree in a series
of sub-directories.

The branch name and ballast structure created by both scripts
match, so either script can be used to generate very large
test repositories for the following perf test.

Created t/perf/p0006-read-tree-checkout.sh to measure
performance on various read-tree, checkout, and update-index
operations.  This test can run using either normal repos or
ones from the above scripts.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-04-19 20:33:01 -07:00
Christian Couder
c9d4999155 p0004: make perf test executable
It looks like in 89c3b0ad43 (name-hash: add perf test for lazy_init_name_hash,
2017-03-23) p0004 was not created with the execute unix rights.
Let's fix that.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Acked-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-04-18 19:18:18 -07:00
Jeff Hostetler
950a234cbd string-list: use ALLOC_GROW macro when reallocing string_list
Use ALLOC_GROW() macro when reallocing a string_list array
rather than simply increasing it by 32.  This is a performance
optimization.

During status on a very large repo and there are many changes,
a significant percentage of the total run time is spent
reallocing the wt_status.changes array.

This change decreases the time in wt_status_collect_changes_worktree()
from 125 seconds to 45 seconds on my very large repository.

This produced a modest gain on my 1M file artificial repo, but
broke even on linux.git.

Test                                            HEAD^^            HEAD
---------------------------------------------------------------------------------------
0005.2: read-tree status br_ballast (1000001)   8.29(5.62+2.62)   8.22(5.57+2.63) -0.8%

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-04-15 02:04:41 -07:00
Junio C Hamano
0330344e0f Merge branch 'jh/memihash-opt'
The name-hash used for detecting paths that are different only in
cases (which matter on case insensitive filesystems) has been
optimized to take advantage of multi-threading when it makes sense.

* jh/memihash-opt:
  name-hash: add test-lazy-init-name-hash to .gitignore
  name-hash: add perf test for lazy_init_name_hash
  name-hash: add test-lazy-init-name-hash
  name-hash: perf improvement for lazy_init_name_hash
  hashmap: document memihash_cont, hashmap_disallow_rehash api
  hashmap: add disallow_rehash setting
  hashmap: allow memihash computation to be continued
  name-hash: specify initial size for istate.dir_hash table
2017-03-28 14:06:00 -07:00
Jeff Hostetler
89c3b0ad43 name-hash: add perf test for lazy_init_name_hash
Created t/perf/p0004-lazy-init-name-hash.sh test
to demonstrate correctness and performance gains
with the multithreaded version of lazy_init_name_hash().

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-03-24 11:00:03 -07:00
Junio C Hamano
5296357386 Merge branch 'dp/filter-branch-prune-empty'
"git filter-branch --prune-empty" drops a single-parent commit that
becomes a no-op, but did not drop a root commit whose tree is empty.

* dp/filter-branch-prune-empty:
  p7000: add test for filter-branch with --prune-empty
  filter-branch: fix --prune-empty on parentless commits
  t7003: ensure --prune-empty removes entire branch when applicable
  t7003: ensure --prune-empty can prune root commit
2017-03-14 15:23:19 -07:00
Devin J. Pohly
32da7467eb p7000: add test for filter-branch with --prune-empty
Signed-off-by: Devin J. Pohly <djpohly@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-03-03 12:43:37 -08:00
Jeff King
28e1fb5466 t/perf: add fallback for pre-bin-wrappers versions of git
It's tempting to say:

  ./run v1.0.0 HEAD

to see how we've sped up Git over the years. Unfortunately,
this doesn't quite work because versions of Git prior to
v1.7.0 lack bin-wrappers, so our "run" script doesn't
correctly put them in the PATH.

Worse, it means we silently find whatever other "git" is in
the PATH, and produce test results that have no bearing on
what we asked for.

Let's fallback to the main git directory when bin-wrappers
isn't present. Many modern perf scripts won't run with such
an antique version of Git, of course, but at least those
failures are detected and reported (and you're free to write
a limited perf script that works across many versions).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-03-03 10:55:27 -08:00
Jeff King
83d4a409d3 t/perf: use $MODERN_GIT for all repo-copying steps
Since 1a0962dee (t/perf: fix regression in testing older
versions of git, 2016-06-22), we point "$MODERN_GIT" to a
copy of git that matches the t/perf script itself, and which
can be used for tasks outside of the actual timings. This is
needed because the setup done by perf scripts keeps moving
forward in time, and may use features that the older
versions of git we are testing do not have.

That commit used $MODERN_GIT to fix a case where we relied
on the relatively recent --git-path option. But if you go
back further still, there are more problems.

Since 7501b5921 (perf: make the tests work in worktrees,
2016-05-13), we use "git -C", but versions of git older than
44e1e4d67 (git: run in a directory given with -C option,
2013-09-09) don't know about "-C". So testing an old version
of git with a new version of t/perf will fail the setup
step.

We can fix this by using $MODERN_GIT during the setup;
there's no need to use the antique version, since it doesn't
affect the timings. Likewise, we'll adjust the "init"
invocation; antique versions of git called this "init-db".

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-03-03 10:55:26 -08:00
Jonathan Tan
67f2825174 t/perf: export variable used in other blocks
In p0001, a variable was created in a test_expect_success block to be
used in later test_perf blocks, but was not exported. This caused the
variable to not appear in those blocks (this can be verified by writing
'test -n "$commit"' in those blocks), resulting in a slightly different
invocation than what was intended. Export that variable.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-03-03 10:54:42 -08:00
Junio C Hamano
cf36a4dc35 Merge branch 'rs/p5302-create-repositories-before-tests'
Adjust a perf test to new world order where commands that do
require a repository are really strict about having a repository.

* rs/p5302-create-repositories-before-tests:
  p5302: create repositories for index-pack results explicitly
2017-02-10 12:52:25 -08:00
René Scharfe
c86000c1a7 p5302: create repositories for index-pack results explicitly
Before 7176a314 (index-pack: complain when --stdin is used outside of a
repo) index-pack silently created a non-existing target directory; now
the command refuses to work unless it's used against a valid repository.
That causes p5302 to fail, which relies on the former behavior.  Fix it
by setting up the destinations for its performance tests using git init.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-02-06 10:55:25 -08:00
René Scharfe
564e94e619 perf: add basic sort performance test
Add a sort command to test-string-list that reads lines from stdin,
stores them in a string_list and then sorts it.  Use it in a simple
perf test script to measure the performance of string_list_sort().

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-23 11:02:37 -08:00
Junio C Hamano
9fcd14491d Merge branch 'jk/fetch-quick-tag-following'
When fetching from a remote that has many tags that are irrelevant
to branches we are following, we used to waste way too many cycles
when checking if the object pointed at by a tag (that we are not
going to fetch!) exists in our repository too carefully.

* jk/fetch-quick-tag-following:
  fetch: use "quick" has_sha1_file for tag following
2016-10-26 13:14:47 -07:00
Jeff King
5827a03545 fetch: use "quick" has_sha1_file for tag following
When we auto-follow tags in a fetch, we look at all of the
tags advertised by the remote and fetch ones where we don't
already have the tag, but we do have the object it peels to.
This involves a lot of calls to has_sha1_file(), some of
which we can reasonably expect to fail. Since 45e8a74
(has_sha1_file: re-check pack directory before giving up,
2013-08-30), this may cause many calls to
reprepare_packed_git(), which is potentially expensive.

This has gone unnoticed for several years because it
requires a fairly unique setup to matter:

  1. You need to have a lot of packs on the client side to
     make reprepare_packed_git() expensive (the most
     expensive part is finding duplicates in an unsorted
     list, which is currently quadratic).

  2. You need a large number of tag refs on the server side
     that are candidates for auto-following (i.e., that the
     client doesn't have). Each one triggers a re-read of
     the pack directory.

  3. Under normal circumstances, the client would
     auto-follow those tags and after one large fetch, (2)
     would no longer be true. But if those tags point to
     history which is disconnected from what the client
     otherwise fetches, then it will never auto-follow, and
     those candidates will impact it on every fetch.

So when all three are true, each fetch pays an extra
O(nr_tags * nr_packs^2) cost, mostly in string comparisons
on the pack names. This was exacerbated by 47bf4b0
(prepare_packed_git_one: refactor duplicate-pack check,
2014-06-30) which uses a slightly more expensive string
check, under the assumption that the duplicate check doesn't
happen very often (and it shouldn't; the real problem here
is how often we are calling reprepare_packed_git()).

This patch teaches fetch to use HAS_SHA1_QUICK to sacrifice
accuracy for speed, in cases where we might be racy with a
simultaneous repack. This is similar to the fix in 0eeb077
(index-pack: avoid excessive re-reading of pack directory,
2015-06-09). As with that case, it's OK for has_sha1_file()
occasionally say "no I don't have it" when we do, because
the worst case is not a corruption, but simply that we may
fail to auto-follow a tag that points to it.

Here are results from the included perf script, which sets
up a situation similar to the one described above:

Test            HEAD^               HEAD
----------------------------------------------------------
5550.4: fetch   11.21(10.42+0.78)   0.08(0.04+0.02) -99.3%

Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-10-14 11:31:32 -07:00
Junio C Hamano
0c5ff91639 Merge branch 'ks/perf-build-with-autoconf'
Performance tests done via "t/perf" did not use the same set of
build configuration if the user relied on autoconf generated
configuration.

* ks/perf-build-with-autoconf:
  t/perf/run: copy config.mak.autogen & friends to build area
2016-09-21 15:15:27 -07:00
Junio C Hamano
7f109ef54e Merge branch 'ks/pack-objects-bitmap'
Some codepaths in "git pack-objects" were not ready to use an
existing pack bitmap; now they are and as the result they have
become faster.

* ks/pack-objects-bitmap:
  pack-objects: use reachability bitmap index when generating non-stdout pack
  pack-objects: respect --local/--honor-pack-keep/--incremental when bitmap is in use
2016-09-21 15:15:21 -07:00
Kirill Smelkov
cd5c2812b6 t/perf/run: copy config.mak.autogen & friends to build area
Otherwise for people who use autotools-based configure in main worktree,
the performance testing results will be inconsistent as work and build
trees could be using e.g. different optimization levels.

See e.g.

	http://public-inbox.org/git/20160818175222.bmm3ivjheokf2qzl@sigill.intra.peff.net/

for example.

NOTE config.status has to be copied because otherwise without it the build
would want to run reconfigure this way loosing just copied config.mak.autogen.

Signed-off-by: Kirill Smelkov <kirr@nexedi.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-09-15 13:41:11 -07:00
Kirill Smelkov
645c432d61 pack-objects: use reachability bitmap index when generating non-stdout pack
Starting from 6b8fda2d (pack-objects: use bitmaps when packing objects)
if a repository has bitmap index, pack-objects can nicely speedup
"Counting objects" graph traversal phase. That however was done only for
case when resultant pack is sent to stdout, not written into a file.

The reason here is for on-disk repack by default we want:

- to produce good pack (with bitmap index not-yet-packed objects are
  emitted to pack in suboptimal order).

- to use more robust pack-generation codepath (avoiding possible
  bugs in bitmap code and possible bitmap index corruption).

Jeff King further explains:

    The reason for this split is that pack-objects tries to determine how
    "careful" it should be based on whether we are packing to disk or to
    stdout. Packing to disk implies "git repack", and that we will likely
    delete the old packs after finishing. We want to be more careful (so
    as not to carry forward a corruption, and to generate a more optimal
    pack), and we presumably run less frequently and can afford extra CPU.
    Whereas packing to stdout implies serving a remote via "git fetch" or
    "git push". This happens more frequently (e.g., a server handling many
    fetching clients), and we assume the receiving end takes more
    responsibility for verifying the data.

    But this isn't always the case. One might want to generate on-disk
    packfiles for a specialized object transfer. Just using "--stdout" and
    writing to a file is not optimal, as it will not generate the matching
    pack index.

    So it would be useful to have some way of overriding this heuristic:
    to tell pack-objects that even though it should generate on-disk
    files, it is still OK to use the reachability bitmaps to do the
    traversal.

So we can teach pack-objects to use bitmap index for initial object
counting phase when generating resultant pack file too:

- if we take care to not let it be activated under git-repack:

  See above about repack robustness and not forward-carrying corruption.

- if we know bitmap index generation is not enabled for resultant pack:

  The current code has singleton bitmap_git, so it cannot work
  simultaneously with two bitmap indices.

  We also want to avoid (at least with current implementation)
  generating bitmaps off of bitmaps. The reason here is: when generating
  a pack, not-yet-packed objects will be emitted into pack in
  suboptimal order and added to tail of the bitmap as "extended entries".
  When the resultant pack + some new objects in associated repository
  are in turn used to generate another pack with bitmap, the situation
  repeats: new objects are again not emitted optimally and just added to
  bitmap tail - not in recency order.

  So the pack badness can grow over time when at each step we have
  bitmapped pack + some other objects. That's why we want to avoid
  generating bitmaps off of bitmaps, not to let pack badness grow.

- if we keep pack reuse enabled still only for "send-to-stdout" case:

  Because pack-to-file needs to generate index for destination pack, and
  currently on pack reuse raw entries are directly written out to the
  destination pack by write_reused_pack(), bypassing needed for pack index
  generation bookkeeping done by regular codepath in write_one() and
  friends.

  ( In the future we might teach pack-reuse code about cases when index
    also needs to be generated for resultant pack and remove
    pack-reuse-only-for-stdout limitation )

This way for pack-objects -> file we get nice speedup:

    erp5.git[1] (~230MB) extracted from ~ 5GB lab.nexedi.com backup
    repository managed by git-backup[2] via

    time echo 0186ac99 | git pack-objects --revs erp5pack

before:  37.2s
after:   26.2s

And for `git repack -adb` packed git.git

    time echo 5c589a73 | git pack-objects --revs gitpack

before:   7.1s
after:    3.6s

i.e. it can be 30% - 50% speedup for pack extraction.

git-backup extracts many packs on repositories restoration. That was my
initial motivation for the patch.

[1] https://lab.nexedi.com/nexedi/erp5
[2] https://lab.nexedi.com/kirr/git-backup

NOTE

Jeff also suggests that pack.useBitmaps was probably a mistake to
introduce originally. This way we are not adding another config point,
but instead just always default to-file pack-objects not to use bitmap
index: Tools which need to generate on-disk packs with using bitmap, can
pass --use-bitmap-index explicitly. And git-repack does never pass
--use-bitmap-index, so this way we can be sure regular on-disk repacking
remains robust.

NOTE2

`git pack-objects --stdout >file.pack` + `git index-pack file.pack` is much slower
than `git pack-objects file.pack`. Extracting erp5.git pack from
lab.nexedi.com backup repository:

    $ time echo 0186ac99 | git pack-objects --stdout --revs >erp5pack-stdout.pack

    real    0m22.309s
    user    0m21.148s
    sys     0m0.932s

    $ time git index-pack erp5pack-stdout.pack

    real    0m50.873s   <-- more than 2 times slower than time to generate pack itself!
    user    0m49.300s
    sys     0m1.360s

So the time for

    `pack-object --stdout >file.pack` + `index-pack file.pack`  is  72s,

while

    `pack-objects file.pack` which does both pack and index     is  27s.

And even

    `pack-objects --no-use-bitmap-index file.pack`              is  37s.

Jeff explains:

    The packfile does not carry the sha1 of the objects. A receiving
    index-pack has to compute them itself, including inflating and applying
    all of the deltas.

that's why for `git-backup restore` we want to teach `git pack-objects
file.pack` to use bitmaps instead of using `git pack-objects --stdout
>file.pack` + `git index-pack file.pack`.

NOTE3

The speedup is now tracked via t/perf/p5310-pack-bitmaps.sh

    Test                                    56dfeb62          this tree
    --------------------------------------------------------------------------------
    5310.2: repack to disk                  8.98(8.05+0.29)   9.05(8.08+0.33) +0.8%
    5310.3: simulated clone                 2.02(2.27+0.09)   2.01(2.25+0.08) -0.5%
    5310.4: simulated fetch                 0.81(1.07+0.02)   0.81(1.05+0.04) +0.0%
    5310.5: pack to file                    7.58(7.04+0.28)   7.60(7.04+0.30) +0.3%
    5310.6: pack to file (bitmap)           7.55(7.02+0.28)   3.25(2.82+0.18) -57.0%
    5310.8: clone (partial bitmap)          1.83(2.26+0.12)   1.82(2.22+0.14) -0.5%
    5310.9: pack to file (partial bitmap)   6.86(6.58+0.30)   2.87(2.74+0.20) -58.2%

More context:

    http://marc.info/?t=146792101400001&r=1&w=2
    http://public-inbox.org/git/20160707190917.20011-1-kirr@nexedi.com/T/#t

Cc: Vicent Marti <tanoku@gmail.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Kirill Smelkov <kirr@nexedi.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-09-12 13:47:41 -07:00
Junio C Hamano
c4071eace9 Merge branch 'jk/delta-base-cache'
The delta-base-cache mechanism has been a key to the performance in
a repository with a tightly packed packfile, but it did not scale
well even with a larger value of core.deltaBaseCacheLimit.

* jk/delta-base-cache:
  t/perf: add basic perf tests for delta base cache
  delta_base_cache: use hashmap.h
  delta_base_cache: drop special treatment of blobs
  delta_base_cache: use list.h for LRU
  release_delta_base_cache: reuse existing detach function
  clear_delta_base_cache_entry: use a more descriptive name
  cache_or_unpack_entry: drop keep_cache parameter
2016-09-08 21:49:46 -07:00
Junio C Hamano
9010077be2 Merge branch 'kw/patch-ids-optim'
* kw/patch-ids-optim:
  p3400: make test script executable
2016-08-31 10:03:49 -07:00
René Scharfe
ba67504fa8 p3400: make test script executable
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-29 12:57:16 -07:00
Jeff King
c7df68cbca t/perf: add basic perf tests for delta base cache
This just shows off the improvements done by the last few
patches, and gives us a baseline for noticing regressions in
the future. Here are the results with linux.git as the perf
"large repo":

Test                origin                HEAD
-------------------------------------------------------------------
0003.1: log --raw   43.41(40.36+2.69)     33.86(30.96+2.41) -22.0%
0003.2: log -S      313.61(309.74+3.78)   298.75(295.58+3.00) -4.7%

(for a large repo, the "log -S" improvements are greater if
you bump the delta base cache limit, but I think it makes
sense to test the "stock" behavior, since that is what most
people will see).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-23 15:26:16 -07:00
Junio C Hamano
dd610aeda6 Merge branch 'kw/patch-ids-optim'
When "git rebase" tries to compare set of changes on the updated
upstream and our own branch, it computes patch-id for all of these
changes and attempts to find matches. This has been optimized by
lazily computing the full patch-id (which is expensive) to be
compared only for changes that touch the same set of paths.

* kw/patch-ids-optim:
  rebase: avoid computing unnecessary patch IDs
  patch-ids: add flag to create the diff patch id using header only data
  patch-ids: replace the seen indicator with a commit pointer
  patch-ids: stop using a hand-rolled hashmap implementation
2016-08-12 09:47:39 -07:00
Kevin Willford
b3dfeebb92 rebase: avoid computing unnecessary patch IDs
The `rebase` family of Git commands avoid applying patches that were
already integrated upstream. They do that by using the revision walking
option that computes the patch IDs of the two sides of the rebase
(local-only patches vs upstream-only ones) and skipping those local
patches whose patch ID matches one of the upstream ones.

In many cases, this causes unnecessary churn, as already the set of
paths touched by a given commit would suffice to determine that an
upstream patch has no local equivalent.

This hurts performance in particular when there are a lot of upstream
patches, and/or large ones.

Therefore, let's introduce the concept of a "diff-header-only" patch ID,
compare those first, and only evaluate the "full" patch ID lazily.

Please note that in contrast to the "full" patch IDs, those
"diff-header-only" patch IDs are prone to collide with one another, as
adjacent commits frequently touch the very same files. Hence we now
have to be careful to allow multiple hash entries with the same hash.
We accomplish that by using the hashmap_add() function that does not even
test for hash collisions.  This also allows us to evaluate the full patch ID
lazily, i.e. only when we found commits with matching diff-header-only
patch IDs.

We add a performance test that demonstrates ~1-6% improvement.  In
practice this will depend on various factors such as how many upstream
changes and how big those changes are along with whether file system
caches are cold or warm.  As Git's test suite has no way of catching
performance regressions, we also add a regression test that verifies
that the full patch ID computation is skipped when the diff-header-only
computation suffices.

Signed-off-by: Kevin Willford <kcwillford@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-11 14:39:16 -07:00
Jeff King
77023ea3c3 t/perf: add tests for many-pack scenarios
Git's pack storage does efficient (log n) lookups in a
single packfile's index, but if we have multiple packfiles,
we have to linearly search each for a given object.  This
patch introduces some timing tests for cases where we have a
large number of packs, so that we can measure any
improvements we make in the following patches.

The main thing we want to time is object lookup. To do this,
we measure "git rev-list --objects --all", which does a
fairly large number of object lookups (essentially one per
object in the repository).

However, we also measure the time to do a full repack, which
is interesting for two reasons. One is that in addition to
the usual pack lookup, it has its own linear iteration over
the list of packs. And two is that because it it is the tool
one uses to go from an inefficient many-pack situation back
to a single pack, we care about its performance not only at
marginal numbers of packs, but at the extreme cases (e.g.,
if you somehow end up with 5,000 packs, it is the only way
to get back to 1 pack, so we need to make sure it performs
well).

We measure the performance of each command in three
scenarios: 1 pack, 50 packs, and 1,000 packs.

The 1-pack case is a baseline; any optimizations we do to
handle multiple packs cannot possibly perform better than
this.

The 50-pack case is as far as Git should generally allow
your repository to go, if you have auto-gc enabled with the
default settings. So this represents the maximum performance
improvement we would expect under normal circumstances.

The 1,000-pack case is hopefully rare, though I have seen it
in the wild where automatic maintenance was broken for some
time (and the repository continued to receive pushes). This
represents cases where we care less about general
performance, but want to make sure that a full repack
command does not take excessively long.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-29 11:05:06 -07:00
Junio C Hamano
e9a6d71331 Merge branch 'jk/perf-any-version'
Allow t/perf framework to use the features from the most recent
version of Git even when testing an older installed version.

* jk/perf-any-version:
  p4211: explicitly disable renames in no-rename test
  t/perf: fix regression in testing older versions of git
2016-07-11 10:31:06 -07:00
Jeff King
85a727895d p4211: explicitly disable renames in no-rename test
p4211 tests line-log performance both with and without "-M".
In v2.9.0, the case without "-M" appears to have regressed
badly, but that is only because we flipped on renames by
default.

Let's have the test explicitly disable renames to get
consistent timings (and to match the presumed intent of the
test, which is to see the effects with and without renames).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-22 13:47:55 -07:00
Jeff King
1a0962dee5 t/perf: fix regression in testing older versions of git
Commit 7501b59 (perf: make the tests work in worktrees,
2016-05-13) introduced the use of "git rev-parse --git-path"
in the perf-lib setup code. Because the to-be-tested version
of git is at the front of the $PATH when this code runs,
this means we cannot use modern versions of t/perf to test
versions of git older than v2.5.0 (when that option was
introduced).

This is a symptom of a more general problem. The t/perf
suite is essentially independent of git versions, and
ideally we would be able to run the most modern and complete
set of tests across many historical versions (to see how
they compare). But any setup code they run is therefore
required to use the lowest common denominator we expect to
test.

So let's introduce a new variable, $MODERN_GIT, that we can
use both in perf-lib and in the test setup to get a reliable
set of git features (we might change git and break some
tests, of course, but $MODERN_GIT is tied to the same
version of git as the t/perf scripts, so they can be fixed
or adjusted together).

This commit fixes the "--git-path" case, but does not
mass-convert existing setup code to use $MODERN_GIT. Most
setup code is fairly vanilla and will work with effectively
all versions. But now the tool is there to fix any other
issues we find going forward.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-22 13:47:16 -07:00
Johannes Schindelin
e3efa94be9 perf: accommodate for MacOSX
As this developer has no access to MacOSX developer setups anymore,
Travis becomes the best bet to run performance tests on that OS.

However, on MacOSX /usr/bin/time is that good old BSD executable that
no Linux user cares about, as demonstrated by the perf-lib.sh's use
of GNU-ish extensions. And by the hard-coded path.

Let's just work around this issue by using gtime on MacOSX, the
Homebrew-provided GNU implementation onto which pretty much every
MacOSX power user falls back anyway.

To help other developers use Travis to run performance tests on
MacOSX, the .travis.yml file now sports a commented-out line that
installs GNU time via Homebrew.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Reviewed-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-06-21 11:18:17 -07:00
René Scharfe
e2522f2aca perf: make the tests work without a worktree
In regular repositories $source_git and $objects_dir contain relative
paths based on $source.  Go there to allow cp to resolve them.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-05-31 13:44:59 -07:00
Johannes Schindelin
e4cfe74cd0 perf: run "rebase -i" under perf
This developer spent a lot of time trying to speed up the interactive
rebase, in particular on Windows. And will continue to do so.

To make it easier to demonstrate the performance improvement, let's have
a reproducible performance test.

The topic branch we use to test performance was found using these shell
commands (essentially searching for a long-enough topic branch in Git's
own history that touched the same file multiple times):

	git rev-list --parents origin/master |
	grep ' .* ' |
	while read commit rest
	do
		patch_count=$(git rev-list --count $commit^..$commit^2)
		test $patch_count -gt 20 || continue

		merges="$(git rev-list --parents $commit^..$commit^2 |
			grep ' .* ')"
		test -z "$merges" || continue

		patches_per_file="$(git log --pretty=%H --name-only \
				$commit^..$commit^2 |
			grep -v '^$' |
			sort |
			uniq -c -d |
			sort -n -r)"
		test -n "$patches_per_file" &&
		test 20 -lt $(echo "$patches_per_file" |
			sed -n '1s/^ *\([0-9]*\).*/\1/p') || continue

		printf 'commit %s\n%s\n' "$commit" "$patches_per_file"
	done

Note that we can get away with *not* having to reset to the original
branch tip before rebasing: we switch the first two "pick" lines every
time, so we end up with the same patch order after two rebases, and the
complexity of both rebases is equivalent.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-05-13 11:07:12 -07:00
Johannes Schindelin
7501b59210 perf: make the tests work in worktrees
This patch makes perf-lib.sh more robust so that it can run correctly
even inside a worktree. For example, it assumed that $GIT_DIR/objects is
the objects directory (which is not the case for worktrees) and it used
the commondir file verbatim, even if it contained a relative path.

Furthermore, the setup code expected `git rev-parse --git-dir` to spit
out a relative path, which is also not true for worktrees. Let's just
change the code to accept both relative and absolute paths, by avoiding
the `cd` into the copied working directory.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-05-13 11:04:07 -07:00
Johannes Schindelin
fd9dbdfb3d perf: let's disable symlinks when they are not available
We already have a perfectly fine prereq to tell us whether it is safe to
use symlinks. So let's use it.

This fixes the performance tests in Git for Windows' SDK, where symlinks
are not really available ([*1*]). This is not an issue with Git for
Windows itself because it configures core.symlinks=false in its system
config.  However, the system config is disabled for the performance
tests, for obvious reasons: we want them to be independent of the
vagaries of any local configuration.

Footnote *1*: Windows has symbolic links. Git for Windows disables them
by default, though (for example: in standard setups, non-admins lack the
privilege to create symbolic links). For details, see
https://github.com/git-for-windows/git/wiki/Symbolic-Links

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-05-13 11:03:11 -07:00
Jeff King
a2d5156c2b resolve_gitlink_ref: ignore non-repository paths
When we want to look up a submodule ref, we use
get_ref_cache(path) to find or auto-create its ref cache.
But if we feed a path that isn't actually a git repository,
we blindly create the ref cache, and then may die deeper in
the code when we try to access it. This is a problem because
many callers speculatively feed us a path that looks vaguely
like a repository, and expect us to tell them when it is
not.

This patch teaches resolve_gitlink_ref to reject
non-repository paths without creating a ref_cache. This
avoids the die(), and also performs better if you have a
large number of these faux-submodule directories (because
the ref_cache lookup is linear, under the assumption that
there won't be a large number of submodules).

To accomplish this, we also break get_ref_cache into two
pieces: the lookup and auto-creation (the latter is lumped
into create_ref_cache). This lets us first cheaply ask our
cache "is it a submodule we know about?" If so, we can avoid
repeating our filesystem lookup. So lookups of real
submodules are not penalized; they examine the submodule's
.git directory only once.

The test in t3000 demonstrates a case where this improves
correctness (we used to just die). The new perf case in
p7300 shows off the speed improvement in an admittedly
pathological repository:

Test                  HEAD^               HEAD
----------------------------------------------------------------
7300.4: ls-files -o   66.97(66.15+0.87)   0.33(0.08+0.24) -99.5%

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-01-25 11:42:13 -08:00
Jeff King
348d4f2fc5 filter-branch: skip index read/write when possible
If the user specifies an index filter but not a tree filter,
filter-branch cleverly avoids checking out the tree
entirely. But we don't do the next level of optimization: if
you have no index or tree filter, we do not need to read the
index at all.

This can greatly speed up cases where we are only changing
the commit objects (e.g., cementing a graft into place).
Here are numbers from the newly-added perf test:

  Test                  HEAD^              HEAD
  ---------------------------------------------------------------
  7000.2: noop filter   13.81(4.95+0.83)   5.43(0.42+0.43) -60.7%

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-11-06 09:35:49 -08:00
Junio C Hamano
d5ef5f522a Merge branch 'sb/perf-without-installed-git'
Performance-measurement tests did not work without an installed Git.

* sb/perf-without-installed-git:
  t/perf: make runner work even if Git is not installed
2015-10-15 15:43:37 -07:00
Stephan Beyer
31cd128372 t/perf: make runner work even if Git is not installed
aggregate.perl did not work when Git.pm is not installed to a directory
contained in the default Perl library path list or PERLLIB.
This commit prepends the Perl library path of the current Git source
tree to enable this.

Note that this commit adds a hard-coded relative path

  use lib '../../perl/blib/lib';

instead of the flexible environment-based variant

  use lib (split(/:/, $ENV{GITPERLLIB}));

which is used in tests written in Perl.
The hard-coded variant is used because the whole performance test
framework does it that way (and GITPERLLIB is not set there).

Signed-off-by: Stephan Beyer <s-beyer@gmx.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-09-25 10:44:59 -07:00
Junio C Hamano
54d673f25d Merge branch 'ee/clean-remove-dirs'
Replace "is this subdirectory a separate repository that should not
be touched?" check "git clean" does by checking if it has .git/HEAD
using the submodule-related code with a more optimized check.

* ee/clean-remove-dirs:
  read_gitfile_gently: fix use-after-free
  clean: improve performance when removing lots of directories
  p7300: add performance tests for clean
  t7300: add tests to document behavior of clean and nested git
  setup: sanity check file size in read_gitfile_gently
  setup: add gentle version of read_gitfile
2015-08-03 11:01:13 -07:00
Stefan Beller
5330e6e270 p5310: Fix broken && chain in performance test
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-06-26 15:41:50 -07:00
Erik Elfström
f49a5650ab p7300: add performance tests for clean
The tests are run in dry-run mode to avoid having to restore the test
directories for each timed iteration. Using dry-run is an acceptable
compromise since we are mostly interested in the initial computation
of what to clean and not so much in the cleaning it self.

Signed-off-by: Erik Elfström <erik.elfstrom@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-06-15 13:14:18 -07:00
Jeff King
ecb590a9de perf-lib: fix ignored exit code inside loop
When copying the test repository, we try to detect whether
the copy succeeded. However, most of the heavy lifting is
done inside a for loop, where our "break" will lose the exit
code of the failing "cp". We can take advantage of the fact
that we are in a subshell, and just "exit 1" to break out
with a code.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-03-25 10:21:23 -07:00
Junio C Hamano
25f3119000 Merge branch 'jk/repack-pack-writebitmaps-config'
* jk/repack-pack-writebitmaps-config:
  t7700: drop explicit --no-pack-kept-objects from .keep test
  repack: introduce repack.writeBitmaps config option
  repack: simplify handling of --write-bitmap-index
  pack-objects: stop respecting pack.writebitmaps
2014-06-25 12:23:19 -07:00
Jeff King
71d76cb480 repack: introduce repack.writeBitmaps config option
We currently have pack.writeBitmaps, which originally
operated at the pack-objects level. This should really have
been a repack.* option from day one. Let's give it the more
sensible name, but keep the old version as a deprecated
synonym.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-06-10 14:05:19 -07:00
Elia Pinto
4717659144 p5302-pack-index.sh: use the $( ... ) construct for command substitution
The Git CodingGuidelines prefer the $(...) construct for command
substitution instead of using the backquotes `...`.

The backquoted form is the traditional method for command
substitution, and is supported by POSIX.  However, all but the
simplest uses become complicated quickly.  In particular, embedded
command substitutions and/or the use of double quotes require
careful escaping with the backslash character.

The patch was generated by:

for _f in $(find . -name "*.sh")
do
   sed -i 's@`\(.*\)`@$(\1)@g' ${_f}
done

and then carefully proof-read.

Signed-off-by: Elia Pinto <gitter.spiros@gmail.com>
Reviewed-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-04-23 15:17:03 -07:00
Junio C Hamano
0f9e62e084 Merge branch 'jk/pack-bitmap'
Borrow the bitmap index into packfiles from JGit to speed up
enumeration of objects involved in a commit range without having to
fully traverse the history.

* jk/pack-bitmap: (26 commits)
  ewah: unconditionally ntohll ewah data
  ewah: support platforms that require aligned reads
  read-cache: use get_be32 instead of hand-rolled ntoh_l
  block-sha1: factor out get_be and put_be wrappers
  do not discard revindex when re-preparing packfiles
  pack-bitmap: implement optional name_hash cache
  t/perf: add tests for pack bitmaps
  t: add basic bitmap functionality tests
  count-objects: recognize .bitmap in garbage-checking
  repack: consider bitmaps when performing repacks
  repack: handle optional files created by pack-objects
  repack: turn exts array into array-of-struct
  repack: stop using magic number for ARRAY_SIZE(exts)
  pack-objects: implement bitmap writing
  rev-list: add bitmap mode to speed up object lists
  pack-objects: use bitmaps when packing objects
  pack-objects: split add_object_entry
  pack-bitmap: add support for bitmap indexes
  documentation: add documentation for the bitmap format
  ewah: compressed bitmap implementation
  ...
2014-02-27 14:01:48 -08:00
Junio C Hamano
a6bec00145 Merge branch 'jk/mark-edges-uninteresting'
Fix performance regression in v1.8.4.x and later.

* jk/mark-edges-uninteresting:
  list-objects: only look at cmdline trees with edge_hint
  t/perf: time rev-list with UNINTERESTING commits
2014-01-27 10:45:08 -08:00