From dc5d40f5bc4d93dcc57ee82c5ca8d1369055d8cb Mon Sep 17 00:00:00 2001 From: Victoria Dye Date: Thu, 10 Nov 2022 19:06:04 +0000 Subject: read-tree: use 'skip_cache_tree_update' option When running 'read-tree' with a single tree and no prefix, 'prime_cache_tree()' is called after the tree is unpacked. In that situation, skip a redundant call to 'cache_tree_update()' in 'unpack_trees()' by enabling the 'skip_cache_tree_update' unpack option. Removing the redundant cache tree update provides a substantial performance improvement to 'git read-tree ', as shown by a test added to 'p0006-read-tree-checkout.sh': Test before after ---------------------------------------------------------------------- read-tree br_ballast_plus_1 3.94(1.80+1.57) 3.00(1.14+1.28) -23.9% Note that the 'read-tree' in 't1022-read-tree-partial-clone.sh' is updated to read two trees, rather than one. The test was first introduced in d3da223f221 (cache-tree: prefetch in partial clone read-tree, 2021-07-23) to exercise the 'cache_tree_update()' code path, as used in 'git merge'. Since this patch drops the call to 'cache_tree_update()' in single-tree 'git read-tree', change the test to use the two-tree variant so that 'cache_tree_update()' is called as intended. Signed-off-by: Victoria Dye Signed-off-by: Taylor Blau --- builtin/read-tree.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'builtin/read-tree.c') diff --git a/builtin/read-tree.c b/builtin/read-tree.c index f4cbe460b9..45c6652444 100644 --- a/builtin/read-tree.c +++ b/builtin/read-tree.c @@ -249,6 +249,10 @@ int cmd_read_tree(int argc, const char **argv, const char *cmd_prefix) if (opts.debug_unpack) opts.fn = debug_merge; + /* If we're going to prime_cache_tree later, skip cache tree update */ + if (nr_trees == 1 && !opts.prefix) + opts.skip_cache_tree_update = 1; + cache_tree_free(&active_cache_tree); for (i = 0; i < nr_trees; i++) { struct tree *tree = trees[i]; -- cgit v1.3