From b65982b60876c8f5f4d3b2898d5174f4812552b1 Mon Sep 17 00:00:00 2001 From: Junio C Hamano Date: Wed, 20 May 2009 15:57:22 -0700 Subject: 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 --- diff-lib.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'diff-lib.c') diff --git a/diff-lib.c b/diff-lib.c index a310fb2ad..1cb97af22 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; -- cgit v1.2.1 From a0919ced8a5efe938cf97c74a0f851cbbe00aaf6 Mon Sep 17 00:00:00 2001 From: Junio C Hamano Date: Fri, 22 May 2009 23:14:25 -0700 Subject: Avoid "diff-index --cached" optimization under --find-copies-harder When find-copies-harder is in effect, the diff frontends are expected to feed all paths, not just changed paths, to the diffcore, so that copy sources can be picked up. In such a case, not descending into subtrees using the cache-tree information is simply wrong. Signed-off-by: Junio C Hamano --- diff-lib.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'diff-lib.c') diff --git a/diff-lib.c b/diff-lib.c index 1cb97af22..ae75eacbc 100644 --- a/diff-lib.c +++ b/diff-lib.c @@ -446,7 +446,8 @@ 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.diff_index_cached = (cached && + !DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER)); opts.merge = 1; opts.fn = oneway_diff; opts.unpack_data = revs; @@ -503,7 +504,7 @@ 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.diff_index_cached = !DIFF_OPT_TST(opt, FIND_COPIES_HARDER); opts.merge = 1; opts.fn = oneway_diff; opts.unpack_data = &revs; -- cgit v1.2.1