Re: Some git performance measurements..

From: Nicolas Pitre <nico@cam.org>
Date: Nov 29, 2007, 18:52 UTC
Message-ID: <alpine.LFD.0.99999.0711291333460.9605@xanadu.home>
In-Reply-To: <alpine.LFD.0.9999.0711290945060.8458@woody.linux-foundation.org>

On Thu, 29 Nov 2007, Linus Torvalds wrote:

Show 20 quoted lines

> 
> 
> On Thu, 29 Nov 2007, Nicolas Pitre wrote:
> > 
> > Well, see below for the patch that actually split the pack data into 
> > objects of the same type.  Doing that "git checkout" on the kernel tree 
> > did improve things for me although not spectacularly.
> 
> Umm. See my earlier numbers. For "git checkout" with cold cache, the 
> *bulk* of the time is actually the ".gitignore" file lookups, so if you 
> see a three-second improvement out of 17s, it may not look spectacular, 
> but considering that probably 10s of those 17s were something *else* going 
> on, I suspect that if you really did just a plain "git checkout", you 
> actually *do* have a spectacular improvement of roughly 7s -> 4s!
> 
> Try with
> 
> 	time git read-tree -m -u HEAD HEAD > /dev/null
> 
> instead.

Oh!  OK then.

Current, cold cache: 5.248s Current, warm cache: 0.185s

Patched, cold cache: 3.337s Patched, warm cache: 0.183s

So yes, the improvement is more significant then, although the cold cache timings vary quite a lot between successive tries.

Nicolas