On Tue, 16 Feb 2010, Nick Piggin wrote: > Yes we do need to explain the downside of the patch. It is a > heuristic and we can't call either approach perfect. > > The fact is that even if 2 tasks are on completely disjoint > memory policies and never _allocate_ from one another's nodes, > you can still have one task pinning memory of the other task's > node. > > Most shared and userspace-pinnable resources (pagecache, vfs > caches and fds files sockes etc) are allocated by first-touch > basically. > > I don't see much usage of cpusets and oom killer first hand in > my experience, so I am happy to defer to others when it comes > to heuristics. Just so long as we are all aware of the full > story :) > Unless you can present a heuristic that will determine how much memory usage a given task has allocated on nodes in current's zonelist, we must exclude tasks from cpusets with a disjoint set of nodes, otherwise we cannot determine the optimal task to kill. There's a strong possibility that killing a task on a disjoint set of mems will never free memory for current, making it a needless kill. That's a much more serious consequence than not having the patch, in my opinion, than rather simply killing current. -- 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>