On Wed, May 05, 2010 at 11:03:40AM +0100, David Howells wrote: > If the system is as heavily loaded as you say, how do you prevent > writer starvation? Or do things just grind along until sufficient > threads are queued waiting for a write lock? Reader/Writer fairness is not disabled in the general case - it only is for a few specific readers such as /proc/<pid>/maps. In particular, the do_page_fault path, which holds a read lock on mmap_sem for potentially long (~disk latency) periods of times, still uses a fair down_read() call. In comparison, the /proc/<pid>/maps path which we made unfair does not normally hold the mmap_sem for very long (it does not end up hitting disk); so it's been working out well for us in practice. -- Michel "Walken" Lespinasse A program is never fully debugged until the last user dies. -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>