view mercurial/default.d/mergetools.rc @ 35793:4fb2bb61597c

bundle2: increase payload part chunk size to 32kb

Bundle2 payload parts are framed chunks. Esentially, we obtain
data in equal size chunks of size `preferedchunksize` and emit those
to a generator. That generator is fed into a compressor (which can
be the no-op compressor, which just re-emits the generator). And
the output from the compressor likely goes to a file descriptor
or socket.

What this means is that small chunk sizes create more Python objects
and Python function calls than larger chunk sizes. And as we know,
Python object and function call overhead in performance sensitive
code matters (at least with CPython).

This commit increases the bundle2 part payload chunk size from 4k
to 32k. Practically speaking, this means that the chunks we feed
into a compressor (implemented in C code) or feed directly into a
file handle or socket write() are larger. It's possible the chunks
might be larger than what the receiver can handle in one logical
operation. But at that point, we're in C code, which is much more
efficient at dealing with splitting up the chunk and making multiple
function calls than Python is.

A downside to larger chunks is that the receiver has to wait for that
much data to arrive (either raw or from a decompressor) before it
can process the chunk. But 32kb still feels like a small buffer to
have to wait for. And in many cases, the client will convert from
8 read(4096) to 1 read(32768). That's happening in Python land. So
we cut down on the number of Python objects and function calls,
making the client faster as well. I don't think there are any
significant concerns to increasing the payload chunk size to 32kb.

The impact of this change on performance significant. Using `curl`
to obtain a stream clone bundle2 payload from a server on localhost
serving the mozilla-unified repository:

before: 20.78 user; 7.71 system;  80.5 MB/s
after:  13.90 user; 3.51 system; 132 MB/s
legacy:  9.72 user; 8.16 system; 132 MB/s

bundle2 stream clone generation is still more resource intensive than
legacy stream clone (that's likely because of the use of a
util.chunkbuffer). But the throughput is the same. We might
be in territory we're this is effectively a benchmark of the
networking stack or Python's syscall throughput.

From the client perspective, `hg clone -U --stream`:

before: 33.50 user; 7.95 system; 53.3 MB/s
after:  22.82 user; 7.33 system; 72.7 MB/s
legacy: 29.96 user; 7.94 system; 58.0 MB/s

And for `hg clone --stream` with a working directory update of
~230k files:

after:  119.55 user; 26.47 system; 0:57.08 wall
legacy: 126.98 user; 26.94 system; 1:05.56 wall

So, it appears that bundle2's stream clone is now definitively faster
than legacy stream clone!

Differential Revision: https://phab.mercurial-scm.org/D1932

# Some default global settings for common merge tools

[merge-tools]
kdiff3.args=--auto --L1 base --L2 local --L3 other $base $local $other -o $output
kdiff3.regkey=Software\KDiff3
kdiff3.regkeyalt=Software\Wow6432Node\KDiff3
kdiff3.regappend=\kdiff3.exe
kdiff3.fixeol=True
kdiff3.gui=True
kdiff3.diffargs=--L1 $plabel1 --L2 $clabel $parent $child

gvimdiff.args=--nofork -d -g -O $local $other $base
gvimdiff.regkey=Software\Vim\GVim
gvimdiff.regkeyalt=Software\Wow6432Node\Vim\GVim
gvimdiff.regname=path
gvimdiff.priority=-9
gvimdiff.diffargs=--nofork -d -g -O $parent $child

vimdiff.args=$local $other $base -c 'redraw | echomsg "hg merge conflict, type \":cq\" to abort vimdiff"'
vimdiff.check=changed
vimdiff.priority=-10

merge.check=conflicts
merge.priority=-100

gpyfm.gui=True

meld.gui=True
meld.args=--label='local' $local --label='merged' $base --label='other' $other -o $output
meld.check=changed
meld.diffargs=-a --label=$plabel1 $parent --label=$clabel $child

tkdiff.args=$local $other -a $base -o $output
tkdiff.gui=True
tkdiff.priority=-8
tkdiff.diffargs=-L $plabel1 $parent -L $clabel $child

xxdiff.args=--show-merged-pane --exit-with-merge-status --title1 local --title2 base --title3 other --merged-filename $output --merge $local $base $other
xxdiff.gui=True
xxdiff.priority=-8
xxdiff.diffargs=--title1 $plabel1 $parent --title2 $clabel $child

diffmerge.regkey=Software\SourceGear\SourceGear DiffMerge\
diffmerge.regkeyalt=Software\Wow6432Node\SourceGear\SourceGear DiffMerge\
diffmerge.regname=Location
diffmerge.priority=-7
diffmerge.args=-nosplash -merge -title1=local -title2=merged -title3=other $local $base $other -result=$output
diffmerge.check=changed
diffmerge.gui=True
diffmerge.diffargs=--nosplash --title1=$plabel1 --title2=$clabel $parent $child

p4merge.args=$base $local $other $output
p4merge.regkey=Software\Perforce\Environment
p4merge.regkeyalt=Software\Wow6432Node\Perforce\Environment
p4merge.regname=P4INSTROOT
p4merge.regappend=\p4merge.exe
p4merge.gui=True
p4merge.priority=-8
p4merge.diffargs=$parent $child

p4mergeosx.executable = /Applications/p4merge.app/Contents/MacOS/p4merge
p4mergeosx.args = $base $local $other $output
p4mergeosx.gui = True
p4mergeosx.priority=-8
p4mergeosx.diffargs=$parent $child

tortoisemerge.args=/base:$base /mine:$local /theirs:$other /merged:$output
tortoisemerge.regkey=Software\TortoiseSVN
tortoisemerge.regkeyalt=Software\Wow6432Node\TortoiseSVN
tortoisemerge.check=changed
tortoisemerge.gui=True
tortoisemerge.priority=-8
tortoisemerge.diffargs=/base:$parent /mine:$child /basename:$plabel1 /minename:$clabel

ecmerge.args=$base $local $other --mode=merge3 --title0=base --title1=local --title2=other --to=$output
ecmerge.regkey=Software\Elli\xc3\xa9 Computing\Merge
ecmerge.regkeyalt=Software\Wow6432Node\Elli\xc3\xa9 Computing\Merge
ecmerge.gui=True
ecmerge.diffargs=$parent $child --mode=diff2 --title1=$plabel1 --title2=$clabel

# editmerge is a small script shipped in contrib.
# It needs this config otherwise it behaves the same as internal:local
editmerge.args=$output
editmerge.check=changed
editmerge.premerge=keep

filemerge.executable=/Developer/Applications/Utilities/FileMerge.app/Contents/MacOS/FileMerge
filemerge.args=-left $other -right $local -ancestor $base -merge $output
filemerge.gui=True

filemergexcode.executable=/Applications/Xcode.app/Contents/Applications/FileMerge.app/Contents/MacOS/FileMerge
filemergexcode.args=-left $other -right $local -ancestor $base -merge $output
filemergexcode.gui=True

; Windows version of Beyond Compare
beyondcompare3.args=$local $other $base $output /ro /lefttitle=local /centertitle=base /righttitle=other /automerge /reviewconflicts /solo
beyondcompare3.regkey=Software\Scooter Software\Beyond Compare 3
beyondcompare3.regname=ExePath
beyondcompare3.gui=True
beyondcompare3.priority=-2
beyondcompare3.diffargs=/lro /lefttitle=$plabel1 /righttitle=$clabel /solo /expandall $parent $child

; Linux version of Beyond Compare
bcompare.args=$local $other $base -mergeoutput=$output -ro -lefttitle=parent1 -centertitle=base -righttitle=parent2 -outputtitle=merged -automerge -reviewconflicts -solo
bcompare.gui=True
bcompare.priority=-1
bcompare.diffargs=-lro -lefttitle=$plabel1 -righttitle=$clabel -solo -expandall $parent $child

; OS X version of Beyond Compare
bcomposx.executable = /Applications/Beyond Compare.app/Contents/MacOS/bcomp
bcomposx.args=$local $other $base -mergeoutput=$output -ro -lefttitle=parent1 -centertitle=base -righttitle=parent2 -outputtitle=merged -automerge -reviewconflicts -solo
bcomposx.gui=True
bcomposx.priority=-1
bcomposx.diffargs=-lro -lefttitle=$plabel1 -righttitle=$clabel -solo -expandall $parent $child

winmerge.args=/e /x /wl /ub /dl other /dr local $other $local $output
winmerge.regkey=Software\Thingamahoochie\WinMerge
winmerge.regkeyalt=Software\Wow6432Node\Thingamahoochie\WinMerge\
winmerge.regname=Executable
winmerge.check=changed
winmerge.gui=True
winmerge.priority=-10
winmerge.diffargs=/r /e /x /ub /wl /dl $plabel1 /dr $clabel $parent $child

araxis.regkey=SOFTWARE\Classes\TypeLib\{46799e0a-7bd1-4330-911c-9660bb964ea2}\7.0\HELPDIR
araxis.regappend=\ConsoleCompare.exe
araxis.priority=-2
araxis.args=/3 /a2 /wait /merge /title1:"Other" /title2:"Base" /title3:"Local :"$local $other $base $local $output
araxis.checkconflict=True
araxis.binary=True
araxis.gui=True
araxis.diffargs=/2 /wait /title1:$plabel1 /title2:$clabel $parent $child

diffuse.priority=-3
diffuse.args=$local $base $other
diffuse.gui=True
diffuse.diffargs=$parent $child

UltraCompare.regkey=Software\Microsoft\Windows\CurrentVersion\App Paths\UC.exe
UltraCompare.regkeyalt=Software\Wow6432Node\Microsoft\Windows\CurrentVersion\App Paths\UC.exe
UltraCompare.args = $base $local $other -title1 base -title3 other
UltraCompare.priority = -2
UltraCompare.gui = True
UltraCompare.binary = True
UltraCompare.check = conflicts,changed
UltraCompare.diffargs=$child $parent -title1 $clabel -title2 $plabel1