Jan Kara <jack@xxxxxxx> writes: >> I see. So many block layer stuff sounds like broken on corner case? If >> so, I more feel this approach should be temporary workaround, and should >> use another less-blocking approach. > Not many but some... The alternative to less blocking approach is to do > copy-out before a page is submitted for IO (or various middle ground > alternatives of doing sometimes copyout, sometimes blocking...). That costs > some performance as well. We talked about it at LSF and the approach > Darrick is implementing was considered the least intrusive. There's really > no way to fix these corner cases and keep performance. You already considered, to copy only if page was writeback (like copy-on-write). I.e. if page is on I/O, copy, then switch the page for writing new data. Yes, it is complex. But I think blocking and overhead is minimum, and this can be used as infrastructure for copy-on-write FS. Thanks. -- OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx 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>