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b65982b608
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>
57 lines
1.4 KiB
C
57 lines
1.4 KiB
C
#ifndef UNPACK_TREES_H
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#define UNPACK_TREES_H
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#define MAX_UNPACK_TREES 8
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struct unpack_trees_options;
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typedef int (*merge_fn_t)(struct cache_entry **src,
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struct unpack_trees_options *options);
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struct unpack_trees_error_msgs {
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const char *would_overwrite;
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const char *not_uptodate_file;
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const char *not_uptodate_dir;
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const char *would_lose_untracked;
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const char *bind_overlap;
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};
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struct unpack_trees_options {
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unsigned int reset:1,
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merge:1,
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update:1,
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index_only:1,
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nontrivial_merge:1,
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trivial_merges_only:1,
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verbose_update:1,
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aggressive:1,
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skip_unmerged:1,
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initial_checkout:1,
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diff_index_cached:1,
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gently:1;
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const char *prefix;
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int pos;
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struct dir_struct *dir;
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merge_fn_t fn;
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struct unpack_trees_error_msgs msgs;
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int head_idx;
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int merge_size;
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struct cache_entry *df_conflict_entry;
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void *unpack_data;
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struct index_state *dst_index;
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struct index_state *src_index;
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struct index_state result;
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};
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extern int unpack_trees(unsigned n, struct tree_desc *t,
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struct unpack_trees_options *options);
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int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o);
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int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o);
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int bind_merge(struct cache_entry **src, struct unpack_trees_options *o);
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int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o);
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#endif
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