Messages in this thread | | | Date | Tue, 9 Mar 2010 09:50:15 -0600 (CST) | From | Christoph Lameter <> | Subject | Re: [PATCH 1/3] page-allocator: Under memory pressure, wait on pressure to relieve instead of congestion |
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On Mon, 8 Mar 2010, Mel Gorman wrote:
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 30fe668..72465c1 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -398,6 +398,9 @@ struct zone { > unsigned long wait_table_hash_nr_entries; > unsigned long wait_table_bits; > > + /* queue for processes waiting for pressure to relieve */ > + wait_queue_head_t *pressure_wq; > + > /*
The waitqueue is in a zone? But allocation occurs by scanning a list of possible zones.
> +long zonepressure_wait(struct zone *zone, unsigned int order, long timeout)
So zone specific.
> > - if (!page && gfp_mask & __GFP_NOFAIL) > - congestion_wait(BLK_RW_ASYNC, HZ/50); > + if (!page && gfp_mask & __GFP_NOFAIL) { > + /* If still failing, wait for pressure on zone to relieve */ > + zonepressure_wait(preferred_zone, order, HZ/50);
The first zone is special therefore...
What happens if memory becomes available in another zone? Lets say we are waiting on HIGHMEM and memory in ZONE_NORMAL becomes available?
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