Re: pack operation is thrashing my server

On Thu, 14 Aug 2008, Nicolas Pitre wrote:

I disagree.  Well, right _now_ it is not a simple operation.  But if you 
remember, I'm one of the co-investigator of the pack v4 format which 
goal is to make history and tree walking much much cheaper, while making 
their packed representation denser too.

See my other email with profile data and explanation.

Yes, zlib is high up, but it's not dominant to the point where a packfile 
format change would maek a huge difference. You'd still need deltas for 
trees, so even if you replaced zlib with something else, you'd still get a 
large hit.

You do realize that a lot of the zlib costs are due to cache misses, not 
zlib being fundamentally expensive in itself, right? Even if you made the 
zlib CPU costs be zero, you still couldn't avoid the _biggest_ cost.

			Linus