On Fri, Nov 21, 2014 at 01:33:26PM +0800, Ganesh Mahendran wrote: > Hello > > 2014-11-21 11:54 GMT+08:00 Minchan Kim <minchan@xxxxxxxxxx>: > > On Thu, Nov 20, 2014 at 09:21:56PM +0800, Mahendran Ganesh wrote: > >> ZS_SIZE_CLASSES is calc by: > >> ((ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) / ZS_SIZE_CLASS_DELTA + 1) > >> > >> So when i is in [0, ZS_SIZE_CLASSES - 1), the size: > >> size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA > >> will not be greater than ZS_MAX_ALLOC_SIZE > >> > >> This patch removes the unnecessary check. > > > > It depends on ZS_MIN_ALLOC_SIZE. > > For example, we would change min to 8 but MAX is still 4096. > > ZS_SIZE_CLASSES is (4096 - 8) / 16 + 1 = 256 so 8 + 255 * 16 = 4088, > > which exceeds the max. > Here, 4088 is less than MAX(4096). > > ZS_SIZE_CLASSES = (MAX - MIN) / Delta + 1 > So, I think the value of > MIN + (ZS_SIZE_CLASSES - 1) * Delta = > MIN + ((MAX - MIN) / Delta) * Delta = > MAX > will not exceed the MAX You're right. It was complext math for me. I should go back to elementary school. Thanks! Acked-by: Minchan Kim <minchan@xxxxxxxxxx> -- 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=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>