perf: clear vfs audit_cache before each run
When generating a stream clone, we spend a large amount of time auditing path.
Before this changes, the first run was warming the vfs cache for the other
runs, leading to a large runtime difference and a "faulty" reported timing for
the operation.
We now clear this important cache between run to get a more realistic timing.
Below are some example of median time change when clearing these cases. The
maximum time for a run did not changed significantly.
### data-env-vars.name = mozilla-central-2018-08-01-zstd-sparse-revlog
# benchmark.name = hg.perf.exchange.stream.generate
# bin-env-vars.hg.flavor = default
# bin-env-vars.hg.py-re2-module = default
# benchmark.variants.version = latest
no-clearing: 17.289905
cache-clearing: 21.587965 (+24.86%, +4.30)
## data-env-vars.name = mozilla-central-2024-03-22-zstd-sparse-revlog
no-clearing: 32.670748
cache-clearing: 40.467095 (+23.86%, +7.80)
## data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog
no-clearing: 37.838858
cache-clearing: 46.072749 (+21.76%, +8.23)
## data-env-vars.name = mozilla-unified-2024-03-22-zstd-sparse-revlog
no-clearing: 32.969395
cache-clearing: 39.646209 (+20.25%, +6.68)
In addition, this significantly reduce the timing difference between the
performance command, from the perf extensions and a `real `hg bundle` call
producing a stream bundle. Some significant differences remain especially on
the "mozilla-try" repositories, but they are now smaller.
Note that some of that difference will actually not be
attributable to the stream generation (like maybe phases or branch map
computation).
Below are some benchmarks done on a currently draft changeset fixing some
unrelated slowness in `hg bundle` (34a78972af409d1ff37c29e60f6ca811ad1a457d)
### data-env-vars.name = mozilla-central-2018-08-01-zstd-sparse-revlog
# bin-env-vars.hg.flavor = default
# bin-env-vars.hg.py-re2-module = default
hg.perf.exchange.stream.generate: 21.587965
hg.command.bundle: 24.301799 (+12.57%, +2.71)
## data-env-vars.name = mozilla-central-2024-03-22-zstd-sparse-revlog
hg.perf.exchange.stream.generate: 40.467095
hg.command.bundle: 44.831317 (+10.78%, +4.36)
## data-env-vars.name = mozilla-unified-2024-03-22-zstd-sparse-revlog
hg.perf.exchange.stream.generate: 39.646209
hg.command.bundle: 45.395258 (+14.50%, +5.75)
## data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog
hg.perf.exchange.stream.generate: 46.072749
hg.command.bundle: 55.882608 (+21.29%, +9.81)
## data-env-vars.name = mozilla-try-2023-03-22-zlib-general-delta
hg.perf.exchange.stream.generate: 334.716708
hg.command.bundle: 377.856767 (+12.89%, +43.14)
## data-env-vars.name = mozilla-try-2023-03-22-zstd-sparse-revlog
hg.perf.exchange.stream.generate: 302.972301
hg.command.bundle: 326.098755 (+7.63%, +23.13)
this structure seems to tickle a bug in bundle's search for
changesets, so first we have to recreate it
o 8
|
| o 7
| |
| o 6
|/|
o | 5
| |
o | 4
| |
| o 3
| |
| o 2
|/
o 1
|
o 0
$ mkrev()
> {
> revno=$1
> echo "rev $revno"
> echo "rev $revno" > foo.txt
> hg -q ci -m"rev $revno"
> }
setup test repo1
$ hg init repo1
$ cd repo1
$ echo "rev 0" > foo.txt
$ hg ci -Am"rev 0"
adding foo.txt
$ mkrev 1
rev 1
first branch
$ mkrev 2
rev 2
$ mkrev 3
rev 3
back to rev 1 to create second branch
$ hg up -r1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ mkrev 4
rev 4
$ mkrev 5
rev 5
merge first branch to second branch
$ hg up -C -r5
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ HGMERGE=internal:local hg merge
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ echo "merge rev 5, rev 3" > foo.txt
$ hg ci -m"merge first branch to second branch"
one more commit following the merge
$ mkrev 7
rev 7
back to "second branch" to make another head
$ hg up -r5
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ mkrev 8
rev 8
the story so far
$ hg log -G --template "{rev}\n"
@ 8
|
| o 7
| |
| o 6
|/|
o | 5
| |
o | 4
| |
| o 3
| |
| o 2
|/
o 1
|
o 0
check that "hg outgoing" really does the right thing
sanity check of outgoing: expect revs 4 5 6 7 8
$ hg clone -r3 . ../repo2
adding changesets
adding manifests
adding file changes
added 4 changesets with 4 changes to 1 files
new changesets 6ae4cca4e39a:478f191e53f8
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
this should (and does) report 5 outgoing revisions: 4 5 6 7 8
$ hg outgoing --template "{rev}\n" ../repo2
comparing with ../repo2
searching for changes
4
5
6
7
8
test bundle (destination repo): expect 5 revisions
this should bundle the same 5 revisions that outgoing reported, but it
actually bundles 7
$ hg bundle foo.bundle ../repo2
searching for changes
5 changesets found
test bundle (base revision): expect 5 revisions
this should (and does) give exactly the same result as bundle
with a destination repo... i.e. it's wrong too
$ hg bundle --base 3 foo.bundle
5 changesets found
$ cd ..