Re: [PATCH 10/10] mm: vmscan: Move logic from balance_pgdat() tokswapd_shrink_zone()

[Mel Gorman]

On Sun, Mar 17, 2013 at 07:55:54AM -0700, Andi Kleen wrote:
> Mel Gorman <mgorman@xxxxxxx> writes:
> 
> > +
> > +	/*
> > +	 * We put equal pressure on every zone, unless one zone has way too
> > +	 * many pages free already. The "too many pages" is defined as the
> > +	 * high wmark plus a "gap" where the gap is either the low
> > +	 * watermark or 1% of the zone, whichever is smaller.
> > +	 */
> > +	balance_gap = min(low_wmark_pages(zone),
> > +		(zone->managed_pages + KSWAPD_ZONE_BALANCE_GAP_RATIO-1) /
> > +		KSWAPD_ZONE_BALANCE_GAP_RATIO);
> 
> Don't like those hard coded tunables. 1% of a 512GB node can be still
> quite a lot. Shouldn't the low watermark be enough?
> 

1% of 512G would be lot but in that case, it'll use the low watermark as
the balance gap.

-- 
Mel Gorman
SUSE Labs
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