The low- and high-water marks for cache object replacement.
	Replacement begins when the swap (disk) usage is above the
	low-water mark and attempts to maintain utilization near the
	low-water mark.  As swap utilization gets close to high-water
	mark object eviction becomes more aggressive.  If utilization is
	close to the low-water mark less replacement is done each time.

	Defaults are 90% and 95%. If you have a large cache, 5% could be
	hundreds of MB. If this is the case you may wish to set these
	numbers closer together.