Re: performance on repack

From: Nicolas Pitre <nico@cam.org>
Date: Aug 16, 2007, 16:21 UTC
Message-ID: <alpine.LFD.0.999.0708161219340.16727@xanadu.home>
In-Reply-To: <9e4733910708160913i29e18e80v107bcc3732e9db95@mail.gmail.com>

On Thu, 16 Aug 2007, Jon Smirl wrote:

Show 19 quoted lines

> On 8/16/07, Nicolas Pitre <nico@cam.org> wrote:
> > On Thu, 16 Aug 2007, David Kastrup wrote:
> > > If I understand correctly, delta indices
> > > for the search window are kept, and the current file is compared
> > > against them.  Locality might be better if just one delta index gets
> > > calculated and then compared with all _upcoming_ delta candidates in
> > > one go.
> >
> > This appears so obvious that I attempted that a while ago already.
> >
> > The idea turned up to be so complex to implement correctly and produced
> > suboptimal results in practice that I abandoned it.
> 
> In practice it doesn't really matter what you do. Most developers have
> a decent amount of RAM. Disks run at 50MB/sec or more. The entire pack
> file ends up in the kernel disk cache within a few seconds.
> 
> Turning the twenty minute delta search into 6-7 minutes is a much more
> obvious win.

And your point in relation with what was just said is ?

Nicolas