From: Andreas Ericsson Date: Tue, 11 Dec 2007 20:26:35 GMT Subject: Re: Something is broken in repack Message-ID: <475EF27B.7060609@op5.se> In-Reply-To: Nicolas Pitre wrote: > On Tue, 11 Dec 2007, David Miller wrote: > >> From: Nicolas Pitre >> Date: Tue, 11 Dec 2007 12:21:11 -0500 (EST) >> >>> BUT. The point is that repacking the gcc repo using "git repack -a -f >>> --window=250" has a radically different memory usage profile whether you >>> do the repack on the earlier 2.1GB pack or the later 300MB pack. >> If you repack on the smaller pack file, git has to expand more stuff >> internally in order to search the deltas, whereas with the larger pack >> file I bet git has to less often undelta'ify to get base objects blobs >> for delta search. > > Of course. I came to that conclusion two days ago. And despite being > pretty familiar with the involved code (I wrote part of it myself) I > just can't spot anything wrong with it so far. > > But somehow the threading code keep distracting people from that issue > since it gets to do the same work whether or not the source pack is > densely packed or not. > > Nicolas > (who wish he had access to a much faster machine to investigate this issue) If it's still an issue next week, we'll have a 16 core (8 dual-core cpu's) machine with some 32gb of ram in that'll be free for about two days. You'll have to remind me about it though, as I've got a lot on my mind these days. -- Andreas Ericsson andreas.ericsson@op5.se OP5 AB www.op5.se Tel: +46 8-230225 Fax: +46 8-230231