RE:

[Linus Torvalds <torvalds@linux-foundation.org>]

On Thu, 7 May 2009, Bevan Watkiss wrote:
>
> Looking at the trace it does appear that most of this is the lstat.  It's
> the problem of having many tiny files on a network drive, and trying to use
> git for something it's not meant.
> 
> The log has 265430 lines of lstat and 10887 other lines.  If you still want
> the log file I'll strip out the directory names and send it off.

Actually, if it's just the lstat's, then it's not all that interesting any 
more, it's a known problem with at least a known _partial_ solution.

However, I think it turns out that we've only enabled the index preloading 
with "git diff" and "git commit". Not on "git checkout".

So start off doing that

> 	[core]
> 		preloadindex = true

AND apply the following patch to git, and see how much (if any) that 
helps. It sounds like you have a pretty damn large repository, together 
with a slow filesystem. It really could be a big improvement.

The patch is TOTALLY UNTESTED. It also worries me that 'git checkout' 
seems to do _two_ 'lstat()' calls per file. I didn't look any more 
closely, but there may be other issues here.

		Linus

---
 builtin-checkout.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/builtin-checkout.c b/builtin-checkout.c
index 15f0c32..3100ccd 100644
--- a/builtin-checkout.c
+++ b/builtin-checkout.c
@@ -216,7 +216,7 @@ static int checkout_paths(struct tree *source_tree, const char **pathspec,
 	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 
 	newfd = hold_locked_index(lock_file, 1);
-	if (read_cache() < 0)
+	if (read_cache_preload(pathspec) < 0)
 		return error("corrupt index file");
 
 	if (source_tree)
@@ -367,7 +367,7 @@ static int merge_working_tree(struct checkout_opts *opts,
 	int newfd = hold_locked_index(lock_file, 1);
 	int reprime_cache_tree = 0;
 
-	if (read_cache() < 0)
+	if (read_cache_preload(NULL) < 0)
 		return error("corrupt index file");
 
 	cache_tree_free(&active_cache_tree);