Re: [PATCH 45 of 66] remove PG_buddy

Mel Gorman
2010-11-18T16:08:18Z

On Wed, Nov 03, 2010 at 04:28:20PM +0100, Andrea Arcangeli wrote:
> From: Andrea Arcangeli <aarcange@redhat.com>
>
> PG_buddy can be converted to _mapcount == -2. So the PG_compound_lock can be
> added to page->flags without overflowing (because of the sparse section bits
> increasing) with CONFIG_X86_PAE=y and CONFIG_X86_PAT=y. This also has to move
> the memory hotplug code from _mapcount to lru.next to avoid any risk of
> clashes. We can't use lru.next for PG_buddy removal, but memory hotplug can use
> lru.next even more easily than the mapcount instead.
>

Does this make much of a difference? I confess I didn't read the patch closely
because I didn't get the motivation.

--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab