Re: performance on repack

From: Jon Smirl <jonsmirl@gmail.com>
Date: Aug 16, 2007, 16:13 UTC
Message-ID: <9e4733910708160913i29e18e80v107bcc3732e9db95@mail.gmail.com>
In-Reply-To: <alpine.LFD.0.999.0708161103080.16727@xanadu.home>

On 8/16/07, Nicolas Pitre <nico@cam.org> wrote:

Show 11 quoted lines

> 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.

Show 13 quoted lines

>
> See http://marc.info/?l=git&m=114610715706599&w=2 for the details if
> you're interested.
>
> PS: please at least CC me when replying to my mails
>
>
> Nicolas
> -
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-- 
Jon Smirl
jonsmirl@gmail.com