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

[Junio C Hamano <junkio@cox.net>]

Shawn Pearce <spearce@spearce.org> writes:

> Junio C Hamano <junkio@cox.net> wrote:
>> Shawn Pearce <spearce@spearce.org> writes:
>> 
>> > 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).
>> 
>> Sounds good. That is exactly what I was expecting it to be done.
>
> So I have this implemented but its against the 32 bit index.
> It passes the full test suite and appears to be working as intended.

Well, if you are talking about git.git t/ directory, I bet that
"the full test suite" easily fits in a single window so much of
the new code is not exercised, unless you have a runtime option
to make use of very tiny window (32kB would be nice) for testing
;-).

> I am going to rebase the changes to the 64 bit index in `pu`
> and clean up my history.  Its currently one massive commit with
> lots of changes that should be broken down into slightly more
> digestable chunks.

Breaking things up would be nice.  Do you have a good testcase
out of Mozilla repository that _needs_ 64-bit index?  The code
in "pu" uses 64-bit index only 32-bit offset cannot describe the
pack, so I only tested with an artificial case with the kernel
archive with .idx converted with convert-idx to 64-bit.