Mercurial > hg
view tests/test-basic.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 | c84844cd523a |
children |
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Create a repository: #if no-extraextensions $ hg config chgserver.idletimeout=60 devel.all-warnings=true devel.default-date=0 0 extensions.fsmonitor= (fsmonitor !) format.use-dirstate-v2=1 (dirstate-v2 !) largefiles.usercache=$TESTTMP/.cache/largefiles lfs.usercache=$TESTTMP/.cache/lfs ui.slash=True ui.interactive=False ui.detailed-exit-code=True ui.merge=internal:merge ui.mergemarkers=detailed ui.promptecho=True ui.ssh=* (glob) ui.timeout.warn=15 web.address=localhost web\.ipv6=(?:True|False) (re) web.server-header=testing stub value #endif $ hg init t $ cd t Prepare a changeset: $ echo a > a $ hg add a $ hg status A a Writes to stdio succeed and fail appropriately #if devfull $ hg status 2>/dev/full A a $ hg status >/dev/full abort: No space left on device* (glob) [255] #endif #if devfull $ hg status >/dev/full 2>&1 [255] $ hg status ENOENT 2>/dev/full [255] #endif On Python 3, stdio may be None: $ hg debuguiprompt --config ui.interactive=true 0<&- abort: Bad file descriptor (no-rhg !) abort: response expected (rhg !) [255] $ hg version -q 0<&- Mercurial Distributed SCM * (glob) #if py3 no-rhg $ hg version -q 1>&- abort: Bad file descriptor [255] #else $ hg version -q 1>&- #endif $ hg unknown -q 1>&- hg: unknown command 'unknown' (did you mean debugknown?) [10] $ hg version -q 2>&- Mercurial Distributed SCM * (glob) $ hg unknown -q 2>&- [10] $ hg commit -m test This command is ancient: $ hg history changeset: 0:acb14030fe0a tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: test Verify that updating to revision 0 via commands.update() works properly $ cat <<EOF > update_to_rev0.py > from mercurial import commands, hg, ui as uimod > myui = uimod.ui.load() > repo = hg.repository(myui, path=b'.') > commands.update(myui, repo, rev=b"0") > EOF $ hg up null 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ "$PYTHON" ./update_to_rev0.py 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg identify -n 0 Poke around at hashes: $ hg manifest --debug b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644 a $ hg cat a a Verify should succeed: $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files checking dirstate checked 1 changesets with 1 changes to 1 files Repository root: $ hg root $TESTTMP/t $ hg log -l1 -T '{reporoot}\n' $TESTTMP/t $ hg root -Tjson | sed 's|\\\\|\\|g' [ { "hgpath": "$TESTTMP/t/.hg", "reporoot": "$TESTTMP/t", "storepath": "$TESTTMP/t/.hg/store" } ] At the end... $ cd .. Status message redirection: $ hg init empty status messages are sent to stdout by default: $ hg outgoing -R t empty -Tjson 2>/dev/null comparing with empty searching for changes [ { "bookmarks": [], "branch": "default", "date": [0, 0], "desc": "test", "node": "acb14030fe0a21b60322c440ad2d20cf7685a376", "parents": ["0000000000000000000000000000000000000000"], "phase": "draft", "rev": 0, "tags": ["tip"], "user": "test" } ] which can be configured to send to stderr, so the output wouldn't be interleaved: $ cat <<'EOF' >> "$HGRCPATH" > [ui] > message-output = stderr > EOF $ hg outgoing -R t empty -Tjson 2>/dev/null [ { "bookmarks": [], "branch": "default", "date": [0, 0], "desc": "test", "node": "acb14030fe0a21b60322c440ad2d20cf7685a376", "parents": ["0000000000000000000000000000000000000000"], "phase": "draft", "rev": 0, "tags": ["tip"], "user": "test" } ] $ hg outgoing -R t empty -Tjson >/dev/null comparing with empty searching for changes this option should be turned off by HGPLAIN= since it may break scripting use: $ HGPLAIN= hg outgoing -R t empty -Tjson 2>/dev/null comparing with empty searching for changes [ { "bookmarks": [], "branch": "default", "date": [0, 0], "desc": "test", "node": "acb14030fe0a21b60322c440ad2d20cf7685a376", "parents": ["0000000000000000000000000000000000000000"], "phase": "draft", "rev": 0, "tags": ["tip"], "user": "test" } ] but still overridden by --config: $ HGPLAIN= hg outgoing -R t empty -Tjson --config ui.message-output=stderr \ > 2>/dev/null [ { "bookmarks": [], "branch": "default", "date": [0, 0], "desc": "test", "node": "acb14030fe0a21b60322c440ad2d20cf7685a376", "parents": ["0000000000000000000000000000000000000000"], "phase": "draft", "rev": 0, "tags": ["tip"], "user": "test" } ] Invalid ui.message-output option: $ hg log -R t --config ui.message-output=bad abort: invalid ui.message-output destination: bad [255] Underlying message streams should be updated when ui.fout/ferr are set: $ cat <<'EOF' > capui.py > import io > from mercurial import registrar > cmdtable = {} > command = registrar.command(cmdtable) > @command(b'capui', norepo=True) > def capui(ui): > out = ui.fout > ui.fout = io.BytesIO() > ui.status(b'status\n') > ui.ferr = io.BytesIO() > ui.warn(b'warn\n') > out.write(b'stdout: %s' % ui.fout.getvalue()) > out.write(b'stderr: %s' % ui.ferr.getvalue()) > EOF $ hg --config extensions.capui=capui.py --config ui.message-output=stdio capui stdout: status stderr: warn