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largefiles: optimize update speed by only updating changed largefiles
Historically, during 'hg update', every largefile in the working copy was
hashed (which is a very expensive operation on big files) and any
largefiles that did not have a hash that matched their standin were
updated.
This patch optimizes 'hg update' by keeping track of what standins have
changed between the old and new revisions, and only updating the largefiles
that have changed. This saves a lot of time by avoiding the unecessary
calculation of a list of sha1 hashes for big files.
With this patch, the time 'hg update' takes to complete is a function of
how many largefiles need to be updated and what their size is.
Performance tests on a repository with about 80 largefiles ranging from
a few MB to about 97 MB are shown below. The tests show how long it takes
to run 'hg update' with no changes actually being updated.
Mercurial 2.1 release:
$ time hg update
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
getting changed largefiles
0 largefiles updated, 0 removed
real 0m10.045s
user 0m9.367s
sys 0m0.674s
With this patch:
$ time hg update
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
real 0m0.965s
user 0m0.845s
sys 0m0.115s
The same repsoitory, without the largefiles extension enabled:
$ time hg update
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
real 0m0.799s
user 0m0.684s
sys 0m0.111s
So before the patch, 'hg update' with no changes was approximately 9.25s
slower with largefiles enabled. With this patch, it is approximately 0.165s
slower.
| author | Na'Tosha Bard <natosha@unity3d.com> |
|---|---|
| date | Mon, 13 Feb 2012 18:37:07 +0100 |
| parents | 0332f8b44e54 |
| children |
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SVN-fs-dump-format-version: 2 UUID: afeb9c47-92ff-4c0c-9f72-e1f6eb8ac9af Revision-number: 0 Prop-content-length: 56 Content-length: 56 K 8 svn:date V 27 2009-06-21T16:34:55.835945Z PROPS-END Revision-number: 1 Prop-content-length: 112 Content-length: 112 K 7 svn:log V 10 init projA K 10 svn:author V 7 pmezard K 8 svn:date V 27 2009-06-21T16:34:55.909545Z PROPS-END Node-path: branches Node-kind: dir Node-action: add Prop-content-length: 10 Content-length: 10 PROPS-END Node-path: tags Node-kind: dir Node-action: add Prop-content-length: 10 Content-length: 10 PROPS-END Node-path: trunk Node-kind: dir Node-action: add Prop-content-length: 10 Content-length: 10 PROPS-END Revision-number: 2 Prop-content-length: 106 Content-length: 106 K 7 svn:log V 5 hello K 10 svn:author V 7 pmezard K 8 svn:date V 27 2009-06-21T16:34:56.150049Z PROPS-END Node-path: trunk/à Node-kind: dir Node-action: add Prop-content-length: 10 Content-length: 10 PROPS-END Node-path: trunk/à/é Node-kind: file Node-action: add Prop-content-length: 10 Text-content-length: 2 Text-content-md5: e29311f6f1bf1af907f9ef9f44b8328b Text-content-sha1: e983f374794de9c64e3d1c1de1d490c0756eeeff Content-length: 12 PROPS-END d Node-path: trunk/é Node-kind: file Node-action: add Prop-content-length: 10 Text-content-length: 2 Text-content-md5: 9ffbf43126e33be52cd2bf7e01d627f9 Text-content-sha1: 094e3afb2fe8dfe82f63731cdcd3b999f4856cff Content-length: 12 PROPS-END e Revision-number: 3 Prop-content-length: 112 Content-length: 112 K 7 svn:log V 10 copy files K 10 svn:author V 7 pmezard K 8 svn:date V 27 2009-06-21T16:34:59.089402Z PROPS-END Node-path: trunk/è Node-kind: file Node-action: add Node-copyfrom-rev: 2 Node-copyfrom-path: trunk/é Text-copy-source-md5: 9ffbf43126e33be52cd2bf7e01d627f9 Text-copy-source-sha1: 094e3afb2fe8dfe82f63731cdcd3b999f4856cff Node-path: trunk/ù Node-kind: dir Node-action: add Node-copyfrom-rev: 2 Node-copyfrom-path: trunk/à Node-path: trunk/à Node-action: delete Node-path: trunk/é Node-action: delete Revision-number: 4 Prop-content-length: 114 Content-length: 114 K 7 svn:log V 12 remove files K 10 svn:author V 7 pmezard K 8 svn:date V 27 2009-06-21T16:35:00.165121Z PROPS-END Node-path: trunk/è Node-action: delete Node-path: trunk/ù Node-action: delete Revision-number: 5 Prop-content-length: 120 Content-length: 120 K 7 svn:log V 18 branch to branché K 10 svn:author V 7 pmezard K 8 svn:date V 27 2009-06-21T16:35:03.079138Z PROPS-END Node-path: branches/branché Node-kind: dir Node-action: add Node-copyfrom-rev: 4 Node-copyfrom-path: trunk Revision-number: 6 Prop-content-length: 121 Content-length: 121 K 7 svn:log V 19 branch to branchée K 10 svn:author V 7 pmezard K 8 svn:date V 27 2009-06-21T16:35:06.060801Z PROPS-END Node-path: branches/branchée Node-kind: dir Node-action: add Node-copyfrom-rev: 5 Node-copyfrom-path: branches/branché Revision-number: 7 Prop-content-length: 110 Content-length: 110 K 7 svn:log V 9 tag trunk K 10 svn:author V 7 pmezard K 8 svn:date V 27 2009-06-21T16:35:09.061530Z PROPS-END Node-path: tags/branché Node-kind: dir Node-action: add Node-copyfrom-rev: 6 Node-copyfrom-path: trunk Revision-number: 8 Prop-content-length: 114 Content-length: 114 K 7 svn:log V 12 tag branché K 10 svn:author V 7 pmezard K 8 svn:date V 27 2009-06-21T16:35:11.068562Z PROPS-END Node-path: tags/branchée Node-kind: dir Node-action: add Node-copyfrom-rev: 6 Node-copyfrom-path: branches/branchée