This instance will be upgraded to Heptapod 0.25.0 (final) on 2021-09-22 at 15:00 UTC+2 (a few minutes of down time)

Commit 3f241f62 authored by Gregory Szorc's avatar Gregory Szorc
Browse files

perf: add perfrevlogrevision

As part of investigating performance improvements to revlog reading,
I needed a mechanism to measure every part of revlog reading so I knew
where time was spent and how effective optimizations were.

This patch implements a perf command for benchmarking the various
stages of reading a single revlog revision.

When executed against a manifest revision at the end of a 30,000+
long delta chain in mozilla-central, the command demonstrates that
~80% of time is spent in zlib decompression.
parent 8914296e74a2
......@@ -2,12 +2,14 @@
'''helper extension to measure performance'''
from mercurial import cmdutil, scmutil, util, commands, obsolete
from mercurial import repoview, branchmap, merge, copies, error
from mercurial import repoview, branchmap, merge, copies, error, revlog
from mercurial import mdiff
import time, os, sys
import random
import functools
formatteropts = commands.formatteropts
revlogopts = commands.debugrevlogopts
cmdtable = {}
command = cmdutil.command(cmdtable)
......@@ -488,6 +490,96 @@ def perfrevlog(ui, repo, file_, **opts):
@command('perfrevlogrevision', revlogopts + formatteropts +
[('', 'cache', False, 'use caches instead of clearing')],
'-c|-m|FILE REV')
def perfrevlogrevision(ui, repo, file_, rev=None, cache=None, **opts):
"""Benchmark obtaining a revlog revision.
Obtaining a revlog revision consists of roughly the following steps:
1. Compute the delta chain
2. Obtain the raw chunks for that delta chain
3. Decompress each raw chunk
4. Apply binary patches to obtain fulltext
5. Verify hash of fulltext
This command measures the time spent in each of these phases.
if opts.get('changelog') or opts.get('manifest'):
file_, rev = None, file_
elif rev is None:
raise error.CommandError('perfrevlogrevision', 'invalid arguments')
r = cmdutil.openrevlog(repo, 'perfrevlogrevision', file_, opts)
node = r.lookup(rev)
rev = r.rev(node)
def dodeltachain(rev):
if not cache:
def doread(chain):
if not cache:
r._chunkraw(chain[0], chain[-1])
def dodecompress(data, chain):
if not cache:
start = r.start
length = r.length
inline = r._inline
iosize = r._io.size
buffer = util.buffer
offset = start(chain[0])
for rev in chain:
chunkstart = start(rev)
if inline:
chunkstart += (rev + 1) * iosize
chunklength = length(rev)
b = buffer(data, chunkstart - offset, chunklength)
def dopatch(text, bins):
if not cache:
mdiff.patches(text, bins)
def dohash(text):
if not cache:
r._checkhash(text, node, rev)
def dorevision():
if not cache:
chain = r._deltachain(rev)[0]
data = r._chunkraw(chain[0], chain[-1])
bins = r._chunks(chain)
text = str(bins[0])
bins = bins[1:]
text = mdiff.patches(text, bins)
benches = [
(lambda: dorevision(), 'full'),
(lambda: dodeltachain(rev), 'deltachain'),
(lambda: doread(chain), 'read'),
(lambda: dodecompress(data, chain), 'decompress'),
(lambda: dopatch(text, bins), 'patch'),
(lambda: dohash(text), 'hash'),
for fn, title in benches:
timer, fm = gettimer(ui, opts)
timer(fn, title=title)
[('C', 'clear', False, 'clear volatile cache between each call.'),
('', 'contexts', False, 'obtain changectx for each revision')]
......@@ -91,6 +91,8 @@ perfstatus
(no help text available)
perfrawfiles (no help text available)
perfrevlog (no help text available)
Benchmark obtaining a revlog revision.
perfrevrange (no help text available)
perfrevset benchmark the execution time of a revset
perfstartup (no help text available)
......@@ -136,6 +138,7 @@ perfstatus
$ hg perfpathcopies 1 2
$ hg perfrawfiles 2
$ hg perfrevlog .hg/store/data/a.i
$ hg perfrevlogrevision -m 0
$ hg perfrevrange
$ hg perfrevset 'all()'
$ hg perfstartup
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