# [PATCH] relax delta selection filtering in pack-objects 4 messages from 2006-02-22 to 2006-02-22. Participants: Nicolas Pitre, Junio C Hamano. Thread: https://gitlist.dev/t/3429 ## Nicolas Pitre, 2006-02-22 01:39 Subject: [PATCH] relax delta selection filtering in pack-objects Message-ID: URL: https://gitlist.dev/e/Pine.LNX.4.64.0602212034180.5606%40localhost.localdomain ``` This change provides a 8% saving on the pack size with a 4% CPU time increase for git-repack -a on the current git archive. Signed-off-by: Nicolas Pitre --- pack-objects.c | 5 ++--- 1 files changed, 2 insertions(+), 3 deletions(-) 2aed7126f9b44d9ef953e8a1cbeab34356410842 diff --git a/pack-objects.c b/pack-objects.c index ceb107f..4f8814d 100644 --- a/pack-objects.c +++ b/pack-objects.c @@ -748,11 +748,10 @@ static int try_delta(struct unpacked *cu } size = cur_entry->size; - if (size < 50) - return -1; oldsize = old_entry->size; sizediff = oldsize > size ? oldsize - size : size - oldsize; - if (sizediff > size / 8) + + if (size < 50) return -1; if (old_entry->depth >= max_depth) return 0; -- 1.2.2.g6643-dirty ``` ## Junio C Hamano, 2006-02-22 06:05 Subject: Re: [PATCH] relax delta selection filtering in pack-objects Message-ID: <7vpslgrkr0.fsf@assigned-by-dhcp.cox.net> URL: https://gitlist.dev/e/7vpslgrkr0.fsf%40assigned-by-dhcp.cox.net In-Reply-To: ``` I haven't dug into the issue yet, but these four delta series seem to break the testsuite. ``` ## Junio C Hamano, 2006-02-22 07:23 Subject: Re: [PATCH] relax delta selection filtering in pack-objects Message-ID: <7vhd6rsvqd.fsf@assigned-by-dhcp.cox.net> URL: https://gitlist.dev/e/7vhd6rsvqd.fsf%40assigned-by-dhcp.cox.net In-Reply-To: <7vpslgrkr0.fsf@assigned-by-dhcp.cox.net> ``` Junio C Hamano writes: > I haven't dug into the issue yet, but these four delta series > seem to break the testsuite. I bisected. It is the adler32 one -- since it makes the generated delta much smaller, it is understandable that it would interact with the break/rename heuristics. It is not strictly breakage in that sense -- we just need to readjust the heuristics thresholds for those algorithms. ``` ## Nicolas Pitre, 2006-02-22 16:04 Subject: Re: [PATCH] relax delta selection filtering in pack-objects Message-ID: URL: https://gitlist.dev/e/Pine.LNX.4.64.0602221058320.5606%40localhost.localdomain In-Reply-To: <7vhd6rsvqd.fsf@assigned-by-dhcp.cox.net> ``` On Tue, 21 Feb 2006, Junio C Hamano wrote: > Junio C Hamano writes: > > > I haven't dug into the issue yet, but these four delta series > > seem to break the testsuite. > > I bisected. It is the adler32 one -- since it makes the > generated delta much smaller, it is understandable that it would > interact with the break/rename heuristics. It is not strictly > breakage in that sense -- we just need to readjust the > heuristics thresholds for those algorithms. I had a quick look and that code rather looks like black magic to me atm. I however found a memory leak in diffcore-rename.c:estimate_similarity(): delta = diff_delta(src->data, src->size, dst->data, dst->size, &delta_size, delta_limit); if (!delta) /* If delta_limit is exceeded, we have too much differences */ return 0; /* A delta that has a lot of literal additions would have * big delta_size no matter what else it does. */ if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE) return 0; \________ delta memory is leaked. Nicolas ```