On Sat, Jun 16, 2012 at 12:56 PM, Wanpeng Li <liwp.linux@xxxxxxxxx> wrote: >>-#define SWP_TYPE_SHIFT(e) (sizeof(e.val) * 8 - MAX_SWAPFILES_SHIFT) >>+#define SWP_TYPE_SHIFT(e) ((sizeof(e.val) * 8) - \ >>+ (MAX_SWAPFILES_SHIFT + RADIX_TREE_EXCEPTIONAL_SHIFT)) > > Hi Hugh, > > Since SHIFT == MAX_SWAPFILES_SHIFT + RADIX_TREE_EXCEPTIONAL_SHIFT == 7 > and the low two bits used for radix_tree, the available swappages number > based of 32bit architectures reduce to 2^(32-7-2) = 32GB? > The lower two bits are in the 7 bits you calculated, so it is 2^(32-7), not 2^(32-7-2) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href