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)
#require no-windows
$ . "$TESTDIR/remotefilelog-library.sh"
$ hg init master
$ cd master
$ cat >> .hg/hgrc <<EOF
> [remotefilelog]
> server=True
> EOF
$ echo x > x
$ hg commit -qAm x
$ echo y > y
$ rm x
$ hg commit -qAm DxAy
$ echo yy > y
$ hg commit -qAm y
$ cd ..
$ hgcloneshallow ssh://user@dummy/master shallow -q
1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
# Set the prefetchdays config to zero so that all commits are prefetched
# no matter what their creation date is.
$ cd shallow
$ cat >> .hg/hgrc <<EOF
> [remotefilelog]
> prefetchdays=0
> EOF
$ cd ..
# Prefetch all data and repack
$ cd shallow
$ cat >> .hg/hgrc <<EOF
> [remotefilelog]
> bgprefetchrevs=all()
> EOF
$ hg prefetch
2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)
$ hg repack
$ find $CACHEDIR | sort | grep -E ".datapack|.histpack"
$TESTTMP/hgcache/master/packs/7bcd2d90b99395ca43172a0dd24e18860b2902f9.histpack
$TESTTMP/hgcache/master/packs/dc8f8fdc76690ce27791ce9f53a18da379e50d37.datapack
# Ensure that all file versions were prefetched
$ hg debugdatapack `ls -ct $TESTTMP/hgcache/master/packs/*.datapack | head -n 1`
$TESTTMP/hgcache/master/packs/dc8f8fdc76690ce27791ce9f53a18da379e50d37:
x:
Node Delta Base Delta Length Blob Size
1406e7411862 000000000000 2 2
Total: 2 2 (0.0% bigger)
y:
Node Delta Base Delta Length Blob Size
50dbc4572b8e 000000000000 3 3
076f5e2225b3 50dbc4572b8e 14 2
Total: 17 5 (240.0% bigger)
# Test garbage collection during repack
$ cat >> .hg/hgrc <<EOF
> [remotefilelog]
> bgprefetchrevs=tip
> gcrepack=True
> nodettl=86400
> EOF
$ hg repack
$ find $CACHEDIR | sort | grep -E ".datapack|.histpack"
$TESTTMP/hgcache/master/packs/7bcd2d90b99395ca43172a0dd24e18860b2902f9.histpack
$TESTTMP/hgcache/master/packs/a4e1d094ec2aee8a08a4d6d95a13c634cc7d7394.datapack
# Ensure that file 'x' was garbage collected. It should be GCed because it is not in the keepset
# and is old (commit date is 0.0 in tests). Ensure that file 'y' is present as it is in the keepset.
$ hg debugdatapack `ls -ct $TESTTMP/hgcache/master/packs/*.datapack | head -n 1`
$TESTTMP/hgcache/master/packs/a4e1d094ec2aee8a08a4d6d95a13c634cc7d7394:
y:
Node Delta Base Delta Length Blob Size
50dbc4572b8e 000000000000 3 3
Total: 3 3 (0.0% bigger)
# Prefetch all data again and repack for later garbage collection
$ cat >> .hg/hgrc <<EOF
> [remotefilelog]
> bgprefetchrevs=all()
> EOF
$ hg prefetch
2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)
$ hg repack
$ find $CACHEDIR | sort | grep -E ".datapack|.histpack"
$TESTTMP/hgcache/master/packs/7bcd2d90b99395ca43172a0dd24e18860b2902f9.histpack
$TESTTMP/hgcache/master/packs/dc8f8fdc76690ce27791ce9f53a18da379e50d37.datapack
# Ensure that all file versions were prefetched
$ hg debugdatapack `ls -ct $TESTTMP/hgcache/master/packs/*.datapack | head -n 1`
$TESTTMP/hgcache/master/packs/dc8f8fdc76690ce27791ce9f53a18da379e50d37:
x:
Node Delta Base Delta Length Blob Size
1406e7411862 000000000000 2 2
Total: 2 2 (0.0% bigger)
y:
Node Delta Base Delta Length Blob Size
50dbc4572b8e 000000000000 3 3
076f5e2225b3 50dbc4572b8e 14 2
Total: 17 5 (240.0% bigger)
# Test garbage collection during repack. Ensure that new files are not removed even though they are not in the keepset
# For the purposes of the test the TTL of a file is set to current time + 100 seconds. i.e. all commits in tests have
# a date of 1970 and therefore to prevent garbage collection we have to set nodettl to be farther from 1970 than we are now.
$ cat >> .hg/hgrc <<EOF
> [remotefilelog]
> bgprefetchrevs=
> nodettl=$(($(date +%s) + 100))
> EOF
$ hg repack
$ find $CACHEDIR | sort | grep -E ".datapack|.histpack"
$TESTTMP/hgcache/master/packs/7bcd2d90b99395ca43172a0dd24e18860b2902f9.histpack
$TESTTMP/hgcache/master/packs/dc8f8fdc76690ce27791ce9f53a18da379e50d37.datapack
# Ensure that all file versions were prefetched
$ hg debugdatapack `ls -ct $TESTTMP/hgcache/master/packs/*.datapack | head -n 1`
$TESTTMP/hgcache/master/packs/dc8f8fdc76690ce27791ce9f53a18da379e50d37:
x:
Node Delta Base Delta Length Blob Size
1406e7411862 000000000000 2 2
Total: 2 2 (0.0% bigger)
y:
Node Delta Base Delta Length Blob Size
50dbc4572b8e 000000000000 3 3
076f5e2225b3 50dbc4572b8e 14 2
Total: 17 5 (240.0% bigger)