Re: [2.4] heavy-load under swap space shortage

[Andrea Arcangeli <andrea@suse.de>]

Hi Nick,

On Mon, Mar 15, 2004 at 03:38:51PM +1100, Nick Piggin wrote:
> 
> 
> Andrea Arcangeli wrote:
> 
> >
> >I don't see other ways to optimize it (and I never enjoyed too much the
> >per-zone lru since it has some downside too with a worst case on 2G
> >systems). peraphs a further optimization could be a transient per-cpu
> >lru refiled only by the page reclaim (so absolutely lazy while lots of
> >ram is free), but maybe that's already what you're doing when you say
> >"Adding/removing sixteen pages for one taking of the lock". Though the
> >fact you say "sixteen pages" sounds like it's not as lazy as it could
> >be.
> >
> 
> Hi Andrea,
> What are the downsides on a 2G system?

it is the absolutely worst case since both lru could be of around the same
size (800M zone-normal-lru and 1.2G zone-highmem-lru), maximizing the
loss of "age" information needed for optimal reclaim decisions.