Mercurial > hg
view contrib/revsetbenchmarks.py @ 30442:41a8106789ca
util: implement zstd compression engine
Now that zstd is vendored and being built (in some configurations), we
can implement a compression engine for zstd!
The zstd engine is a little different from existing engines. Because
it may not always be present, we have to defer load the module in case
importing it fails. We facilitate this via a cached property that holds
a reference to the module or None. The "available" method is
implemented to reflect reality.
The zstd engine declares its ability to handle bundles using the
"zstd" human name and the "ZS" internal name. The latter was chosen
because internal names are 2 characters (by only convention I think)
and "ZS" seems reasonable.
The engine, like others, supports specifying the compression level.
However, there are no consumers of this API that yet pass in that
argument. I have plans to change that, so stay tuned.
Since all we need to do to support bundle generation with a new
compression engine is implement and register the compression engine,
bundle generation with zstd "just works!" Tests demonstrating this
have been added.
How does performance of zstd for bundle generation compare? On the
mozilla-unified repo, `hg bundle --all -t <engine>-v2` yields the
following on my i7-6700K on Linux:
engine CPU time bundle size vs orig size throughput
none 97.0s 4,054,405,584 100.0% 41.8 MB/s
bzip2 (l=9) 393.6s 975,343,098 24.0% 10.3 MB/s
gzip (l=6) 184.0s 1,140,533,074 28.1% 22.0 MB/s
zstd (l=1) 108.2s 1,119,434,718 27.6% 37.5 MB/s
zstd (l=2) 111.3s 1,078,328,002 26.6% 36.4 MB/s
zstd (l=3) 113.7s 1,011,823,727 25.0% 35.7 MB/s
zstd (l=4) 116.0s 1,008,965,888 24.9% 35.0 MB/s
zstd (l=5) 121.0s 977,203,148 24.1% 33.5 MB/s
zstd (l=6) 131.7s 927,360,198 22.9% 30.8 MB/s
zstd (l=7) 139.0s 912,808,505 22.5% 29.2 MB/s
zstd (l=12) 198.1s 854,527,714 21.1% 20.5 MB/s
zstd (l=18) 681.6s 789,750,690 19.5% 5.9 MB/s
On compression, zstd for bundle generation delivers:
* better compression than gzip with significantly less CPU utilization
* better than bzip2 compression ratios while still being significantly
faster than gzip
* ability to aggressively tune compression level to achieve
significantly smaller bundles
That last point is important. With clone bundles, a server can
pre-generate a bundle file, upload it to a static file server, and
redirect clients to transparently download it during clone. The server
could choose to produce a zstd bundle with the highest compression
settings possible. This would take a very long time - a magnitude
longer than a typical zstd bundle generation - but the result would
be hundreds of megabytes smaller! For the clone volume we do at
Mozilla, this could translate to petabytes of bandwidth savings
per year and faster clones (due to smaller transfer size).
I don't have detailed numbers to report on decompression. However,
zstd decompression is fast: >1 GB/s output throughput on this machine,
even through the Python bindings. And it can do that regardless of the
compression level of the input. By the time you have enough data to
worry about overhead of decompression, you have plenty of other things
to worry about performance wise.
zstd is wins all around. I can't wait to implement support for it
on the wire protocol and in revlogs.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Fri, 11 Nov 2016 01:10:07 -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()