From a1dab41af4c575bb72231c73df26ecb2af4814d6 Mon Sep 17 00:00:00 2001 From: Brian Downing Date: Thu, 12 Jul 2007 07:55:47 -0500 Subject: [PATCH] Don't try to delta if target is much smaller than source Add a new try_delta heuristic. Don't bother trying to make a delta if the target object size is much smaller (currently 1/32) than the source, as it's very likely not going to get a match. Even if it does, you will have to read at least 32x the size of the new file to reassemble it, which isn't such a good deal. This leads to a considerable performance improvement when deltifying a mix of small and large files with a very large window, because you don't have to wait for the large files to percolate out of the window before things start going fast again. Signed-off-by: Brian Downing Acked-by: Nicolas Pitre Signed-off-by: Junio C Hamano --- builtin-pack-objects.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c index b4f3e7c2eb..54f304c115 100644 --- a/builtin-pack-objects.c +++ b/builtin-pack-objects.c @@ -1348,6 +1348,8 @@ static int try_delta(struct unpacked *trg, struct unpacked *src, sizediff = src_size < trg_size ? trg_size - src_size : 0; if (sizediff >= max_size) return 0; + if (trg_size < src_size / 32) + return 0; /* Load data if not already done */ if (!trg->data) { -- 2.11.4.GIT