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

Rik van Riel
2007-03-02T21:20:50Z

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.

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...

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