From: Michael Haggerty <mhagger@xxxxxxxxxxxx>
It might seem like allocating a fixed-length buffer of uninitialized
memory should be pretty cheap even if the buffer is of size PATH_MAX.
But empirically, it is measurably faster to allocated only the strlen
of the input string.
Thanks to Peff for pointing out a performance regression in this area
that might be fixed by this patch.
Signed-off-by: Michael Haggerty <mhagger@xxxxxxxxxxxx>
---
I am not able to reproduce performance regressions as bad as those
observed by Peff. It seems to depend on the amount of memory
pressure. The smaller regression that I *did* see is fixed by this
patch, reducing the time for "git fetch . refs/*:refs/*" from 10.1 s
to 9.3 s. The change is sensible in any case, but we will have to
wait for Peff's verdict about whether it fixes the whole problem for
him, too.
refs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/refs.c b/refs.c
index d6bdb47..fffbb17 100644
--- a/refs.c
+++ b/refs.c
@@ -383,7 +383,7 @@ static struct ref_dir *find_containing_dir(struct ref_dir *dir,
{
struct strbuf dirname;
const char *slash;
- strbuf_init(&dirname, PATH_MAX);
+ strbuf_init(&dirname, strlen(refname));
for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
struct ref_dir *subdir;
strbuf_add(&dirname,
--
1.7.10
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