path: root/compat/vcbuild/include/alloca.h
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authorKirill Smelkov <>2014-02-24 16:21:51 (GMT)
committerJunio C Hamano <>2014-04-07 21:41:49 (GMT)
commit7195fbfaf5a539b8e8358097e02b63991e78a565 (patch)
tree5fb4ddafccf80986e24b40c29ebafefecf643d51 /compat/vcbuild/include/alloca.h
parent72441af7c4e3bde33cdf7edafcf09c227d5d5296 (diff)
combine-diff: speed it up, by using multiparent diff tree-walker directly
As was recently shown in "combine-diff: optimize combine_diff_path sets intersection", combine-diff runs very slowly. In that commit we optimized paths sets intersection, but that accounted only for ~ 25% of the slowness, and as my tracing showed, for linux.git v3.10..v3.11, for merges a lot of time is spent computing diff(commit,commit^2) just to only then intersect that huge diff to almost small set of files from diff(commit,commit^1). In previous commit, we described the problem in more details, and reworked the diff tree-walker to be general one - i.e. to work in multiple parent case too. Now is the time to take advantage of it for finding paths for combine diff. The implementation is straightforward - if we know, we can get generated diff paths directly, and at present that means no diff filtering or rename/copy detection was requested(*), we can call multiparent tree-walker directly and get ready paths. (*) because e.g. at present, all diffcore transformations work on diff_filepair queues, but in the future, that limitation can be lifted, if filters would operate directly on combine_diff_paths. Timings for `git log --raw --no-abbrev --no-renames` without `-c` ("git log") and with `-c` ("git log -c") and with `-c --merges` ("git log -c --merges") before and after the patch are as follows: linux.git v3.10..v3.11 log log -c log -c --merges before 1.9s 16.4s 15.2s after 1.9s 2.4s 1.1s The result stayed the same. Signed-off-by: Kirill Smelkov <> Signed-off-by: Junio C Hamano <>
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