Re: [RFC] Cache negative delta pairs

On Thu, Jun 29, 2006 at 12:39:31PM -0400, Nicolas Pitre wrote:

You do that lookup for every delta match attempt.  Instead it could be 
done once for the whole window attempt, potentially reducing the cache 
size by a factor of 20, and it might be faster too.

I'm not convinced this will provide good cache hit characteristics, and
I'm not convinced it's semantically correct (see my other mail).

You could simply recreate the cache on each run.  Or just keep a bitmap 

Yes, that would probably work and would be quite easy to do with the
existing code.

First, I think it should be ignored (but still created) when 
--no-reuse-delta is passed.  Then, it should not be created (but still 
looked up if it exists and --no-reuse-delta is not provided) when the 
pack index file is also not created.  I don't think it is worth making 
this further configurable, and given the suggested strategy above the 
cache should remain fairly small.

Those suggestions make sense to me.

-Peff