>>>> and adding new syscall invokation is unwelcome. >>> >>> Sure. But one more system call could be cheaper than page-granuarity >>> operation on purged range. >> >> I don't think vrange(VOLATILE) cost is the related of this discusstion. >> Whether sending SIGBUS or just nuke pte, purge should be done on vmscan, >> not vrange() syscall. > > Again, please see the MADV_FREE. http://lwn.net/Articles/230799/ > It does changes pte and page flags on all pages of the range through > zap_pte_range. So it would make vrange(VOLASTILE) expensive and > the bigger cost is, the bigger range is. This haven't been crossed my mind. now try_to_discard_one() insert vrange for making SIGBUS. then, we can insert pte_none() as the same cost too. Am I missing something? I couldn't imazine why pte should be zapping on vrange(VOLATILE). -- 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>