Mercurial > hg
view contrib/revsetbenchmarks.py @ 30818:4c0a5a256ae8
localrepo: experimental support for non-zlib revlog compression
The final part of integrating the compression manager APIs into
revlog storage is the plumbing for repositories to advertise they
are using non-zlib storage and for revlogs to instantiate a non-zlib
compression engine.
The main intent of the compression manager work was to zstd all
of the things. Adding zstd to revlogs has proved to be more involved
than other places because revlogs are... special. Very small inputs
and the use of delta chains (which are themselves a form of
compression) are a completely different use case from streaming
compression, which bundles and the wire protocol employ. I've
conducted numerous experiments with zstd in revlogs and have yet
to formalize compression settings and a storage architecture that
I'm confident I won't regret later. In other words, I'm not yet
ready to commit to a new mechanism for using zstd - or any other
compression format - in revlogs.
That being said, having some support for zstd (and other compression
formats) in revlogs in core is beneficial. It can allow others to
conduct experiments.
This patch introduces *highly experimental* support for non-zlib
compression formats in revlogs. Introduced is a config option to
control which compression engine to use. Also introduced is a namespace
of "exp-compression-*" requirements to denote support for non-zlib
compression in revlogs. I've prefixed the namespace with "exp-"
(short for "experimental") because I'm not confident of the
requirements "schema" and in no way want to give the illusion of
supporting these requirements in the future. I fully intend to drop
support for these requirements once we figure out what we're doing
with zstd in revlogs.
A good portion of the patch is teaching the requirements system
about registered compression engines and passing the requested
compression engine as an opener option so revlogs can instantiate
the proper compression engine for new operations.
That's a verbose way of saying "we can now use zstd in revlogs!"
On an `hg pull` conversion of the mozilla-unified repo with no extra
redelta settings (like aggressivemergedeltas), we can see the impact
of zstd vs zlib in revlogs:
$ hg perfrevlogchunks -c
! chunk
! wall 2.032052 comb 2.040000 user 1.990000 sys 0.050000 (best of 5)
! wall 1.866360 comb 1.860000 user 1.820000 sys 0.040000 (best of 6)
! chunk batch
! wall 1.877261 comb 1.870000 user 1.860000 sys 0.010000 (best of 6)
! wall 1.705410 comb 1.710000 user 1.690000 sys 0.020000 (best of 6)
$ hg perfrevlogchunks -m
! chunk
! wall 2.721427 comb 2.720000 user 2.640000 sys 0.080000 (best of 4)
! wall 2.035076 comb 2.030000 user 1.950000 sys 0.080000 (best of 5)
! chunk batch
! wall 2.614561 comb 2.620000 user 2.580000 sys 0.040000 (best of 4)
! wall 1.910252 comb 1.910000 user 1.880000 sys 0.030000 (best of 6)
$ hg perfrevlog -c -d 1
! wall 4.812885 comb 4.820000 user 4.800000 sys 0.020000 (best of 3)
! wall 4.699621 comb 4.710000 user 4.700000 sys 0.010000 (best of 3)
$ hg perfrevlog -m -d 1000
! wall 34.252800 comb 34.250000 user 33.730000 sys 0.520000 (best of 3)
! wall 24.094999 comb 24.090000 user 23.320000 sys 0.770000 (best of 3)
Only modest wins for the changelog. But manifest reading is
significantly faster. What's going on?
One reason might be data volume. zstd decompresses faster. So given
more bytes, it will put more distance between it and zlib.
Another reason is size. In the current design, zstd revlogs are
*larger*:
debugcreatestreamclonebundle (size in bytes)
zlib: 1,638,852,492
zstd: 1,680,601,332
I haven't investigated this fully, but I reckon a significant cause of
larger revlogs is that the zstd frame/header has more bytes than
zlib's. For very small inputs or data that doesn't compress well, we'll
tend to store more uncompressed chunks than with zlib (because the
compressed size isn't smaller than original). This will make revlog
reading faster because it is doing less decompression.
Moving on to bundle performance:
$ hg bundle -a -t none-v2 (total CPU time)
zlib: 102.79s
zstd: 97.75s
So, marginal CPU decrease for reading all chunks in all revlogs
(this is somewhat disappointing).
$ hg bundle -a -t <engine>-v2 (total CPU time)
zlib: 191.59s
zstd: 115.36s
This last test effectively measures the difference between zlib->zlib
and zstd->zstd for revlogs to bundle. This is a rough approximation of
what a server does during `hg clone`.
There are some promising results for zstd. But not enough for me to
feel comfortable advertising it to users. We'll get there...
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Fri, 13 Jan 2017 20:16:56 -0800 |
parents | 984c4d23d39c |
children | e2697acd9381 |
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#!/usr/bin/env python # Measure the performance of a list of revsets against multiple revisions # defined by parameter. Checkout one by one and run perfrevset with every # revset in the list to benchmark its performance. # # You should run this from the root of your mercurial repository. # # call with --help for details from __future__ import absolute_import, print_function import math import optparse # cannot use argparse, python 2.7 only import os import re import subprocess import sys DEFAULTVARIANTS = ['plain', 'min', 'max', 'first', 'last', 'reverse', 'reverse+first', 'reverse+last', 'sort', 'sort+first', 'sort+last'] def check_output(*args, **kwargs): kwargs.setdefault('stderr', subprocess.PIPE) kwargs.setdefault('stdout', subprocess.PIPE) proc = subprocess.Popen(*args, **kwargs) output, error = proc.communicate() if proc.returncode != 0: raise subprocess.CalledProcessError(proc.returncode, ' '.join(args[0])) return output def update(rev): """update the repo to a revision""" try: subprocess.check_call(['hg', 'update', '--quiet', '--check', str(rev)]) check_output(['make', 'local'], stderr=None) # suppress output except for error/warning except subprocess.CalledProcessError as exc: print('update to revision %s failed, aborting'%rev, file=sys.stderr) sys.exit(exc.returncode) def hg(cmd, repo=None): """run a mercurial command <cmd> is the list of command + argument, <repo> is an optional repository path to run this command in.""" fullcmd = ['./hg'] if repo is not None: fullcmd += ['-R', repo] fullcmd += ['--config', 'extensions.perf=' + os.path.join(contribdir, 'perf.py')] fullcmd += cmd return check_output(fullcmd, stderr=subprocess.STDOUT) def perf(revset, target=None, contexts=False): """run benchmark for this very revset""" try: args = ['perfrevset', revset] if contexts: args.append('--contexts') output = hg(args, repo=target) return parseoutput(output) except subprocess.CalledProcessError as exc: print('abort: cannot run revset benchmark: %s'%exc.cmd, file=sys.stderr) if getattr(exc, 'output', None) is None: # no output before 2.7 print('(no output)', file=sys.stderr) else: print(exc.output, file=sys.stderr) return None outputre = re.compile(r'! wall (\d+.\d+) comb (\d+.\d+) user (\d+.\d+) ' 'sys (\d+.\d+) \(best of (\d+)\)') def parseoutput(output): """parse a textual output into a dict We cannot just use json because we want to compare with old versions of Mercurial that may not support json output. """ match = outputre.search(output) if not match: print('abort: invalid output:', file=sys.stderr) print(output, file=sys.stderr) sys.exit(1) return {'comb': float(match.group(2)), 'count': int(match.group(5)), 'sys': float(match.group(3)), 'user': float(match.group(4)), 'wall': float(match.group(1)), } def printrevision(rev): """print data about a revision""" sys.stdout.write("Revision ") sys.stdout.flush() subprocess.check_call(['hg', 'log', '--rev', str(rev), '--template', '{if(tags, " ({tags})")} ' '{rev}:{node|short}: {desc|firstline}\n']) def idxwidth(nbidx): """return the max width of number used for index This is similar to log10(nbidx), but we use custom code here because we start with zero and we'd rather not deal with all the extra rounding business that log10 would imply. """ nbidx -= 1 # starts at 0 idxwidth = 0 while nbidx: idxwidth += 1 nbidx //= 10 if not idxwidth: idxwidth = 1 return idxwidth def getfactor(main, other, field, sensitivity=0.05): """return the relative factor between values for 'field' in main and other Return None if the factor is insignificant (less than <sensitivity> variation).""" factor = 1 if main is not None: factor = other[field] / main[field] low, high = 1 - sensitivity, 1 + sensitivity if (low < factor < high): return None return factor def formatfactor(factor): """format a factor into a 4 char string 22% 156% x2.4 x23 x789 x1e4 x5x7 """ if factor is None: return ' ' elif factor < 2: return '%3i%%' % (factor * 100) elif factor < 10: return 'x%3.1f' % factor elif factor < 1000: return '%4s' % ('x%i' % factor) else: order = int(math.log(factor)) + 1 while 1 < math.log(factor): factor //= 0 return 'x%ix%i' % (factor, order) def formattiming(value): """format a value to strictly 8 char, dropping some precision if needed""" if value < 10**7: return ('%.6f' % value)[:8] else: # value is HUGE very unlikely to happen (4+ month run) return '%i' % value _marker = object() def printresult(variants, idx, data, maxidx, verbose=False, reference=_marker): """print a line of result to stdout""" mask = '%%0%ii) %%s' % idxwidth(maxidx) out = [] for var in variants: if data[var] is None: out.append('error ') out.append(' ' * 4) continue out.append(formattiming(data[var]['wall'])) if reference is not _marker: factor = None if reference is not None: factor = getfactor(reference[var], data[var], 'wall') out.append(formatfactor(factor)) if verbose: out.append(formattiming(data[var]['comb'])) out.append(formattiming(data[var]['user'])) out.append(formattiming(data[var]['sys'])) out.append('%6d' % data[var]['count']) print(mask % (idx, ' '.join(out))) def printheader(variants, maxidx, verbose=False, relative=False): header = [' ' * (idxwidth(maxidx) + 1)] for var in variants: if not var: var = 'iter' if 8 < len(var): var = var[:3] + '..' + var[-3:] header.append('%-8s' % var) if relative: header.append(' ') if verbose: header.append('%-8s' % 'comb') header.append('%-8s' % 'user') header.append('%-8s' % 'sys') header.append('%6s' % 'count') print(' '.join(header)) def getrevs(spec): """get the list of rev matched by a revset""" try: out = check_output(['hg', 'log', '--template={rev}\n', '--rev', spec]) except subprocess.CalledProcessError as exc: print("abort, can't get revision from %s"%spec, file=sys.stderr) sys.exit(exc.returncode) return [r for r in out.split() if r] def applyvariants(revset, variant): if variant == 'plain': return revset for var in variant.split('+'): revset = '%s(%s)' % (var, revset) return revset helptext="""This script will run multiple variants of provided revsets using different revisions in your mercurial repository. After the benchmark are run summary output is provided. Use it to demonstrate speed improvements or pin point regressions. Revsets to run are specified in a file (or from stdin), one revsets per line. Line starting with '#' will be ignored, allowing insertion of comments.""" parser = optparse.OptionParser(usage="usage: %prog [options] <revs>", description=helptext) parser.add_option("-f", "--file", help="read revset from FILE (stdin if omitted)", metavar="FILE") parser.add_option("-R", "--repo", help="run benchmark on REPO", metavar="REPO") parser.add_option("-v", "--verbose", action='store_true', help="display all timing data (not just best total time)") parser.add_option("", "--variants", default=','.join(DEFAULTVARIANTS), help="comma separated list of variant to test " "(eg: plain,min,sorted) (plain = no modification)") parser.add_option('', '--contexts', action='store_true', help='obtain changectx from results instead of integer revs') (options, args) = parser.parse_args() if not args: parser.print_help() sys.exit(255) # the directory where both this script and the perf.py extension live. contribdir = os.path.dirname(__file__) revsetsfile = sys.stdin if options.file: revsetsfile = open(options.file) revsets = [l.strip() for l in revsetsfile if not l.startswith('#')] revsets = [l for l in revsets if l] print("Revsets to benchmark") print("----------------------------") for idx, rset in enumerate(revsets): print("%i) %s" % (idx, rset)) print("----------------------------") print() revs = [] for a in args: revs.extend(getrevs(a)) variants = options.variants.split(',') results = [] for r in revs: print("----------------------------") printrevision(r) print("----------------------------") update(r) res = [] results.append(res) printheader(variants, len(revsets), verbose=options.verbose) for idx, rset in enumerate(revsets): varres = {} for var in variants: varrset = applyvariants(rset, var) data = perf(varrset, target=options.repo, contexts=options.contexts) varres[var] = data res.append(varres) printresult(variants, idx, varres, len(revsets), verbose=options.verbose) sys.stdout.flush() print("----------------------------") print(""" Result by revset ================ """) print('Revision:') for idx, rev in enumerate(revs): sys.stdout.write('%i) ' % idx) sys.stdout.flush() printrevision(rev) print() print() for ridx, rset in enumerate(revsets): print("revset #%i: %s" % (ridx, rset)) printheader(variants, len(results), verbose=options.verbose, relative=True) ref = None for idx, data in enumerate(results): printresult(variants, idx, data[ridx], len(results), verbose=options.verbose, reference=ref) ref = data[ridx] print()