Re: [RFC] My research agenda for 2.7

[Daniel Phillips <phillips@arcor.de>]

On Wednesday 25 June 2003 03:10, William Lee Irwin III wrote:
> On Wednesday 25 June 2003 02:47, William Lee Irwin III wrote:
> >> Per struct address_space? This is an unnecessary limitation.
>
> On Wed, Jun 25, 2003 at 03:07:18AM +0200, Daniel Phillips wrote:
> > It's a sensible limitation, it keeps the radix tree lookup simple.
>
> It severely limits its usefulness. Dropping in a more flexible data
> structure should be fine.

Eventually it could well make sense to do that, e.g., the radix tree 
eventually ought to evolve into a btree of extents (probably).  But making 
things so complex in the first version, thus losing much of the incremental 
development advantage, would not be smart.  With a single size of page per 
address_space,  changes to the radix tree code are limited to a couple of 
lines, for example.

But perhaps you'd like to supply some examples where more than one size of 
page in the same address space really matters?

> On Wednesday 25 June 2003 02:47, William Lee Irwin III wrote:
> >> This gives me the same data structure proliferation chills as bh's.
>
> On Wed, Jun 25, 2003 at 03:07:18AM +0200, Daniel Phillips wrote:
> > It's not nearly as bad.  There is no distinction between subpage and base
> > struct page for almost all page operations, e.g., locking, IO, data
> > access.
>
> But those are code sanitation issues. You need to make sure this
> doesn't explode on PAE.

Indeed, that is important.  Good night, see you tomorrow.

Daniel