Re: [PATCH 1/3] page-allocator: Under memory pressure, wait onpressure to relieve instead of congestion

[Christoph Lameter]

On Tue, 9 Mar 2010, Mel Gorman wrote:

> Until it's timeout at least. It's still better than the current
> situation of sleeping on congestion.

Congestion may clear if memory becomes available in other zones.

> The ideal would be waiting on a per-node basis. I'm just not liking having
> to look up the node structure when freeing a patch of pages and making a
> cache line in there unnecessarily hot.

The node structure (pgdat) contains the zone structures. If you know the
type of zone then you can calculate the pgdat address.

> > But then an overallocated node may stall processes. If that node is full
> > of unreclaimable memory then the process may never wake up?
> Processes wake after a timeout.

Ok that limits it but still we may be waiting for no reason.

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