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

[Nick Piggin]

Rik van Riel wrote:

> On Mon, 15 Mar 2004, Andrea Arcangeli wrote:
>
>
> > 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.
>
> You only lose age information if you don't put equal aging
> pressure on both zones.  If you make sure the allocation and
> pageout pressure are more or less in line with the zone sizes,
> why would you lose any aging information ?

I can't see that you would, no. But maybe I've missed something.
We apply pressure equally except when there is a shortage in a
low memory zone, in which case we can scan only the required
zone(s).

This case I think is well worth the unfairness it causes, because it
means your zone's pages can be freed quickly and without freeing pages
from other zones.

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