will select "node" order in following case.
(1) if the DMA zone does not exist or
(2) if the DMA zone comprises greater than 50% of the available memory or
-(3) if any node's DMA zone comprises greater than 60% of its local memory and
+(3) if any node's DMA zone comprises greater than 70% of its local memory and
the amount of local memory is big enough.
Otherwise, "zone" order will be selected. Default order is recommended unless