On Mon, Mar 19, 2012 at 02:26:34PM +0100, Peter Zijlstra wrote: > So what about the case where all I do is compile kernels and we already > have near perfect locality because everything is short running? You're > still scanning that memory, and I get no benefit. I could add an option to delay the scan and enable it only on long lived "mm". In practice I measured the scanning cost and it was in the unmeasurable range on host this is why I didn't yet, plus I tried to avoid all special cases and to keep things as generic as possible so treating everything the same. Maybe it's good idea, maybe not as it delays more the time it takes to react to wrong memory layout. If you stop knuma_scand with sysfs (echo 0 >...) the whole thing eventually stops. It's like 3 gears, where first gear is knuma_scand, second gear is the numa hinting page fault, the third gears are knuma_migrated and CPU scheduler that gets driven. So it's easy to benchmark the fixed cost. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>