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| author | Junio C Hamano <gitster@pobox.com> | 2009-05-20 15:57:22 -0700 |
|---|---|---|
| committer | Junio C Hamano <gitster@pobox.com> | 2009-05-25 11:35:29 -0700 |
| commit | b65982b60876c8f5f4d3b2898d5174f4812552b1 (patch) | |
| tree | 2589a99c5824624b4ff66249fd64214da84b1da1 /diff-lib.c | |
| parent | aceae2ef9261718324bf1853401d5ee9686a54a8 (diff) | |
| download | git-b65982b60876c8f5f4d3b2898d5174f4812552b1.tar.gz | |
Optimize "diff-index --cached" using cache-tree
When running "diff-index --cached" after making a change to only a small
portion of the index, there is no point unpacking unchanged subtrees into
the index recursively, only to find that all entries match anyway. Tweak
unpack_trees() logic that is used to read in the tree object to catch the
case where the tree entry we are looking at matches the index as a whole
by looking at the cache-tree.
As an exercise, after modifying a few paths in the kernel tree, here are
a few numbers on my Athlon 64X2 3800+:
(without patch, hot cache)
$ /usr/bin/time git diff --cached --raw
:100644 100644 b57e1f5... e69de29... M Makefile
:100644 000000 8c86b72... 0000000... D arch/x86/Makefile
:000000 100644 0000000... e69de29... A arche
0.07user 0.02system 0:00.09elapsed 102%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+9407minor)pagefaults 0swaps
(with patch, hot cache)
$ /usr/bin/time ../git.git/git-diff --cached --raw
:100644 100644 b57e1f5... e69de29... M Makefile
:100644 000000 8c86b72... 0000000... D arch/x86/Makefile
:000000 100644 0000000... e69de29... A arche
0.02user 0.00system 0:00.02elapsed 103%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+2446minor)pagefaults 0swaps
Cold cache numbers are very impressive, but it does not matter very much
in practice:
(without patch, cold cache)
$ su root sh -c 'echo 3 >/proc/sys/vm/drop_caches'
$ /usr/bin/time git diff --cached --raw
:100644 100644 b57e1f5... e69de29... M Makefile
:100644 000000 8c86b72... 0000000... D arch/x86/Makefile
:000000 100644 0000000... e69de29... A arche
0.06user 0.17system 0:10.26elapsed 2%CPU (0avgtext+0avgdata 0maxresident)k
247032inputs+0outputs (1172major+8237minor)pagefaults 0swaps
(with patch, cold cache)
$ su root sh -c 'echo 3 >/proc/sys/vm/drop_caches'
$ /usr/bin/time ../git.git/git-diff --cached --raw
:100644 100644 b57e1f5... e69de29... M Makefile
:100644 000000 8c86b72... 0000000... D arch/x86/Makefile
:000000 100644 0000000... e69de29... A arche
0.02user 0.01system 0:01.01elapsed 3%CPU (0avgtext+0avgdata 0maxresident)k
18440inputs+0outputs (79major+2369minor)pagefaults 0swaps
This of course helps "git status" as well.
(without patch, hot cache)
$ /usr/bin/time ../git.git/git-status >/dev/null
0.17user 0.18system 0:00.35elapsed 100%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+5336outputs (0major+10970minor)pagefaults 0swaps
(with patch, hot cache)
$ /usr/bin/time ../git.git/git-status >/dev/null
0.10user 0.16system 0:00.27elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+5336outputs (0major+3921minor)pagefaults 0swaps
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'diff-lib.c')
| -rw-r--r-- | diff-lib.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/diff-lib.c b/diff-lib.c index a310fb2ad0..1cb97af22d 100644 --- a/diff-lib.c +++ b/diff-lib.c @@ -446,6 +446,7 @@ int run_diff_index(struct rev_info *revs, int cached) memset(&opts, 0, sizeof(opts)); opts.head_idx = 1; opts.index_only = cached; + opts.diff_index_cached = cached; opts.merge = 1; opts.fn = oneway_diff; opts.unpack_data = revs; @@ -502,6 +503,7 @@ int do_diff_cache(const unsigned char *tree_sha1, struct diff_options *opt) memset(&opts, 0, sizeof(opts)); opts.head_idx = 1; opts.index_only = 1; + opts.diff_index_cached = 1; opts.merge = 1; opts.fn = oneway_diff; opts.unpack_data = &revs; |