Re: [PATCH] 1/5 VM changes: zone-pressure.patch

[Nikita Danilov]

Andrew Morton writes:
 > Nikita Danilov <[e-mail]> wrote:
 > >
 > >  +	if (priority < 0) {
 > >  +		for (i = 0; i < pgdat->nr_zones; i++) {
 > >  +			struct zone *zone = pgdat->node_zones + i;
 > >  +
 > >  +			if (zone->free_pages < zone->pages_high)
 > >  +				zone_adj_pressure(zone, -1);
 > >  +		}
 > >  +	}
 > 
 > What is this bit doing?

kswapd failed to balance some zone after going up to the maximal
priority (0), increase ->pressure on this zone.

In other words: zone->pressure is average of the scanning priority
required to free enough pages in this zone. As no scanning priority was
enough to free pages, zone->pressure should be extra high.

Nikita.