On 2008.08.14 16:14:26 -0700, Linus Torvalds wrote: > > On Thu, 14 Aug 2008, Nicolas Pitre wrote: > > > > Possible. However, the fact that both the "Compressing objects" and the > > "Writing objects" phases during a repack (without -f) together are > > _faster_ than the "Counting objects" phase is a sign that something is > > more significant than cache misses here, especially when tree > > information is a small portion of the total pack data size. > > Hmm. I think I may have clue. > > The size of the delta cache seems to be a sensitive parameter for this > thing. Not so much for the git archive, but working on the kernel tree, > raising it to 1024 seems to give a 20% performance improvement. That, in > turn, implies that we may be unpacking things over and over again because > of bad locality wrt delta generation. Since you mention the delta cache, uau (no idea about his real name) on #git was talking about some delta cache optimizations lately, although he was dealing with "git log -S", maybe it affects rev-list in a similar way. Unfortunately, I can't seem to find any code for that, just a description of what he did and some numbers on the results in the IRC logs. http://colabti.org/irclogger/irclogger_log/git?date=2008-08-04,Mon#l65 Maybe that helps in some way. Björn -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
