Re: [PATCH 3/5] autoconf: Preliminary check for working mmap

From: Shawn Pearce <spearce@spearce.org>
Date: Sep 5, 2006, 06:25 UTC
Message-ID: <20060905062531.GA30496@spearce.org>
In-Reply-To: <7vu03mkiei.fsf@assigned-by-dhcp.cox.net>

Junio C Hamano <junkio@cox.net> wrote:

Show 12 quoted lines

> Shawn Pearce <spearce@spearce.org> writes:
> 
> > I'm maybe only 1/3 of the way through the sliding window mmap
> > implementation.  I've got a good chunk of sha1_file.c converted but I
> > still have to deal with the copying in pack-objects.c and the verify
> > code in verify-pack.c.  I'm hoping I can send a preliminary patch
> > series tomorrow as I'm going to work on it more tonight and tomorrow.
> 
> Thanks -- I was tempted to do this myself after finishing the
> index_64 change in "pu" branch, but have resisted the temptation
> myself so far.  Being lazy, the less I have to code the better,
> naturally ;-).

I thought that might be the case. I should be able to finish it up tomorrow. :-)

I don't know if I've made this more complex than I really need to but I've permitted multiple windows per pack. There is just one LRU of all windows across all packs and a maximum amount of address space to use for pack mappings. Least recently used window gets tossed when we need a different window. This permits us to keep say a window active on the front of a pack (near the commits) and another different active window closer to the back (near the blobs).

That multiple window feature made it a slightly non-trivial copy and paste from fast-import but I think its worth it for tree walking type applications.

-- 
Shawn.