Re: Something is broken in repack

> On Tue, 11 Dec 2007, David Miller wrote:
> 
>> From: Nicolas Pitre <nico@cam.org>
>> 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)