Re: The performance and behaviour of the anti-fragmentation related patches

Andrew Morton
2007-03-02T21:53:49Z

On Fri, 02 Mar 2007 16:19:19 -0500
Rik van Riel <riel@redhat.com> wrote:

> Bill Irwin wrote:
> > On Fri, Mar 02, 2007 at 01:23:28PM -0500, Rik van Riel wrote:
> >> With 32 CPUs diving into the page reclaim simultaneously,
> >> each trying to scan a fraction of memory, this is disastrous
> >> for performance. A 256GB system should be even worse.
> >
> > Thundering herds of a sort pounding the LRU locks from direct reclaim
> > have set off the NMI oopser for users here.
>
> Ditto here.

Opterons?

> The main reason they end up pounding the LRU locks is the
> swappiness heuristic. They scan too much before deciding
> that it would be a good idea to actually swap something
> out, and with 32 CPUs doing such scanning simultaneously...

What kernel version?