Mercurial > hg
view tests/test-sqlitestore.t @ 51681:522b4d729e89
mmap: populate the mapping by default
Without pre-population, accessing all data through a mmap can result in many
pagefault, reducing performance significantly. If the mmap is prepopulated, the
performance can no longer get slower than a full read.
(See benchmark number below)
In some cases were very few data is read, prepopulating can be overkill and
slower than populating on access (through page fault). So that behavior can be
controlled when the caller can pre-determine the best behavior.
(See benchmark number below)
In addition, testing with populating in a secondary thread yield great result
combining the best of each approach. This might be implemented in later
changesets.
In all cases, using mmap has a great effect on memory usage when many processes
run in parallel on the same machine.
### Benchmarks
# What did I run
A couple of month back I ran a large benchmark campaign to assess the impact of
various approach for using mmap with the revlog (and other files), it
highlighted a few benchmarks that capture the impact of the changes well. So to
validate this change I checked the following:
- log command displaying various revisions
(read the changelog index)
- log command displaying the patch of listed revisions
(read the changelog index, the manifest index and a few files indexes)
- unbundling a few revisions
(read and write changelog, manifest and few files indexes, and walk the graph
to update some cache)
- pushing a few revisions
(read and write changelog, manifest and few files indexes, walk the graph to
update some cache, performs various accesses locally and remotely during
discovery)
Benchmarks were run using the default module policy (c+py) and the rust one. No
significant difference were found between the two implementation, so we will
present result using the default policy (unless otherwise specified).
I ran them on a few repositories :
- mercurial: a "public changeset only" copy of mercurial from 2018-08-01 using
zstd compression and sparse-revlog
- pypy: a copy of pypy from 2018-08-01 using zstd compression and sparse-revlog
- netbeans: a copy of netbeans from 2018-08-01 using zstd compression and
sparse-revlog
- mozilla-try: a copy of mozilla-try from 2019-02-18 using zstd compression and
sparse-revlog
- mozilla-try persistent-nodemap: Same as the above but with a persistent
nodemap. Used for the log --patch benchmark only
# Results
For the smaller repositories (mercurial, pypy), the impact of mmap is almost
imperceptible, other cost dominating the operation. The impact of prepopulating
is undiscernible in the benchmark we ran.
For larger repositories the benchmark support explanation given above:
On netbeans, the log can be about 1% faster without repopulation (for a
difference < 100ms) but unbundle becomes a bit slower, even when small.
### data-env-vars.name = netbeans-2018-08-01-zstd-sparse-revlog
# benchmark.name = hg.command.unbundle
# benchmark.variants.issue6528 = disabled
# benchmark.variants.reuse-external-delta-parent = yes
# benchmark.variants.revs = any-1-extra-rev
# benchmark.variants.source = unbundle
# benchmark.variants.verbosity = quiet
with-populate: 0.240157
no-populate: 0.265087 (+10.38%, +0.02)
# benchmark.variants.revs = any-100-extra-rev
with-populate: 1.459518
no-populate: 1.481290 (+1.49%, +0.02)
## benchmark.name = hg.command.push
# benchmark.variants.explicit-rev = none
# benchmark.variants.issue6528 = disabled
# benchmark.variants.protocol = ssh
# benchmark.variants.reuse-external-delta-parent = yes
# benchmark.variants.revs = any-1-extra-rev
with-populate: 0.771919
no-populate: 0.792025 (+2.60%, +0.02)
# benchmark.variants.revs = any-100-extra-rev
with-populate: 1.459518
no-populate: 1.481290 (+1.49%, +0.02)
For mozilla-try, the "slow down" from pre-populate for small `hg log` is more
visible, but still small in absolute time. (using rust value for the persistent
nodemap value to be relevant).
### data-env-vars.name = mozilla-try-2019-02-18-ds2-pnm
# benchmark.name = hg.command.log
# bin-env-vars.hg.flavor = rust
# benchmark.variants.patch = yes
# benchmark.variants.limit-rev = 1
with-populate: 0.237813
no-populate: 0.229452 (-3.52%, -0.01)
# benchmark.variants.limit-rev = 10
# benchmark.variants.patch = yes
with-populate: 1.213578
no-populate: 1.205189
### data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog
# benchmark.variants.limit-rev = 1000
# benchmark.variants.patch = no
# benchmark.variants.rev = tip
with-populate: 0.198607
no-populate: 0.195038 (-1.80%, -0.00)
However pre-populating provide a significant boost on more complex operations
like unbundle or push:
### data-env-vars.name = mozilla-try-2019-02-18-zstd-sparse-revlog
# benchmark.name = hg.command.push
# benchmark.variants.explicit-rev = none
# benchmark.variants.issue6528 = disabled
# benchmark.variants.protocol = ssh
# benchmark.variants.reuse-external-delta-parent = yes
# benchmark.variants.revs = any-1-extra-rev
with-populate: 4.798632
no-populate: 4.953295 (+3.22%, +0.15)
# benchmark.variants.revs = any-100-extra-rev
with-populate: 4.903618
no-populate: 5.014963 (+2.27%, +0.11)
## benchmark.name = hg.command.unbundle
# benchmark.variants.revs = any-1-extra-rev
with-populate: 1.423411
no-populate: 1.585365 (+11.38%, +0.16)
# benchmark.variants.revs = any-100-extra-rev
with-populate: 1.537909
no-populate: 1.688489 (+9.79%, +0.15)
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
---|---|
date | Thu, 11 Apr 2024 00:02:07 +0200 |
parents | 7ee07e1a25c0 |
children |
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#require sqlite no-chg The sqlitestore backend leaves transactions around when used with chg. Since this backend is primarily intended as proof-of-concept for alternative storage backends, disable it for chg test runs to avoid the instability. $ cat >> $HGRCPATH <<EOF > [extensions] > sqlitestore = > EOF New repo should not use SQLite by default $ hg init empty-no-sqlite $ hg debugrequires -R empty-no-sqlite dotencode dirstate-v2 (dirstate-v2 !) fncache generaldelta persistent-nodemap (rust !) revlog-compression-zstd (zstd !) revlogv1 share-safe sparserevlog store storage.new-repo-backend=sqlite is recognized $ hg --config storage.new-repo-backend=sqlite init empty-sqlite $ hg debugrequires -R empty-sqlite dotencode dirstate-v2 (dirstate-v2 !) exp-sqlite-001 exp-sqlite-comp-001=zstd (zstd !) exp-sqlite-comp-001=$BUNDLE2_COMPRESSIONS$ (no-zstd !) fncache generaldelta persistent-nodemap (rust !) revlog-compression-zstd (zstd !) revlogv1 share-safe sparserevlog store $ cat >> $HGRCPATH << EOF > [storage] > new-repo-backend = sqlite > EOF Can force compression to zlib $ hg --config storage.sqlite.compression=zlib init empty-zlib $ hg debugrequires -R empty-zlib dotencode dirstate-v2 (dirstate-v2 !) exp-sqlite-001 exp-sqlite-comp-001=$BUNDLE2_COMPRESSIONS$ fncache generaldelta persistent-nodemap (rust !) revlog-compression-zstd (zstd !) revlogv1 share-safe sparserevlog store Can force compression to none $ hg --config storage.sqlite.compression=none init empty-none $ hg debugrequires -R empty-none dotencode dirstate-v2 (dirstate-v2 !) exp-sqlite-001 exp-sqlite-comp-001=none fncache generaldelta persistent-nodemap (rust !) revlog-compression-zstd (zstd !) revlogv1 share-safe sparserevlog store Can make a local commit $ hg init local-commit $ cd local-commit $ echo 0 > foo $ hg commit -A -m initial adding foo That results in a row being inserted into various tables $ sqlite3 .hg/store/db.sqlite -init /dev/null << EOF > SELECT * FROM filepath; > EOF 1|foo $ sqlite3 .hg/store/db.sqlite -init /dev/null << EOF > SELECT * FROM fileindex; > EOF 1|1|0|-1|-1|0|0|1||6/\xef(L\xe2\xca\x02\xae\xcc\x8d\xe6\xd5\xe8\xa1\xc3\xaf\x05V\xfe (esc) $ sqlite3 .hg/store/db.sqlite -init /dev/null << EOF > SELECT * FROM delta; > EOF 1|1| \xd2\xaf\x8d\xd2"\x01\xdd\x8dH\xe5\xdc\xfc\xae\xd2\x81\xff\x94"\xc7|0 (esc) Tracking multiple files works $ echo 1 > bar $ hg commit -A -m 'add bar' adding bar $ sqlite3 .hg/store/db.sqlite -init /dev/null << EOF > SELECT * FROM filedata ORDER BY id ASC; > EOF 1|1|foo|0|6/\xef(L\xe2\xca\x02\xae\xcc\x8d\xe6\xd5\xe8\xa1\xc3\xaf\x05V\xfe|-1|-1|0|0|1| (esc) 2|2|bar|0|\xb8\xe0/d3s\x80!\xa0e\xf9Au\xc7\xcd#\xdb_\x05\xbe|-1|-1|1|0|2| (esc) Multiple revisions of a file works $ echo a >> foo $ hg commit -m 'modify foo' $ sqlite3 .hg/store/db.sqlite -init /dev/null << EOF > SELECT * FROM filedata ORDER BY id ASC; > EOF 1|1|foo|0|6/\xef(L\xe2\xca\x02\xae\xcc\x8d\xe6\xd5\xe8\xa1\xc3\xaf\x05V\xfe|-1|-1|0|0|1| (esc) 2|2|bar|0|\xb8\xe0/d3s\x80!\xa0e\xf9Au\xc7\xcd#\xdb_\x05\xbe|-1|-1|1|0|2| (esc) 3|1|foo|1|\xdd\xb3V\xcd\xde1p@\xf7\x8e\x90\xb8*\x8b,\xe9\x0e\xd6j+|0|-1|2|0|3|1 (esc) $ cd ..