On Fri, 2015-05-08 at 16:03 -0400, Rik van Riel wrote: > This works well when dealing with tasks that are constantly > running, but fails catastrophically when dealing with tasks > that go to sleep, wake back up, go back to sleep, wake back > up, and generally mess up the load statistics that the NUMA > balancing code use in a random way.
Sleeping is what happens a lot I believe in this workload: processes do a lot of network I/O, file I/O too, and a lot of IPC. Would you please expand on this a bit more - why would this scenario "mess up load statistics" ? > If the normal scheduler load balancer is moving tasks the > other way the NUMA balancer is moving them, things will > not converge, and tasks will have worse memory locality > than not doing NUMA balancing at all. Are the regular and NUMA balancers independent? Are there mechanisms to detect ping-pong situations? I'd like to verify your theory, and these kinds of mechanisms would be helpful. > Currently the load balancer has a preference for moving > tasks to their preferred nodes (NUMA_FAVOUR_HIGHER, true), > but there is no resistance to moving tasks away from their > preferred nodes (NUMA_RESIST_LOWER, false). That setting > was arrived at after a fair amount of experimenting, and > is probably correct. I guess I can try making NUMA_RESIST_LOWER to be true and see what happens. But probably first I need to confirm that your theory (balancers playing ping-pong) is correct, any hints on how would I do this? Thanks! Artem. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
