On Thu, 13 Feb 2014, Raghavendra K T wrote: > Thanks David, unfortunately even after applying that patch, I do not see > the improvement. > > Interestingly numa_mem_id() seem to still return the value of a > memoryless node. > May be per cpu _numa_mem_ values are not set properly. Need to dig out .... > I believe ppc will be relying on __build_all_zonelists() to set numa_mem_id() to be the proper node, and that relies on the ordering of the zonelist built for the memoryless node. It would be very strange if local_memory_node() is returning a memoryless node because it is the first zone for node_zonelist(GFP_KERNEL) (why would a memoryless node be on the zonelist at all?). I think the real problem is that build_all_zonelists() is only called at init when the boot cpu is online so it's only setting numa_mem_id() properly for the boot cpu. Does it return a node with memory if you toggle /proc/sys/vm/numa_zonelist_order? Do echo node > /proc/sys/vm/numa_zonelist_order echo zone > /proc/sys/vm/numa_zonelist_order echo default > /proc/sys/vm/numa_zonelist_order and check if it returns the proper value at either point. This will force build_all_zonelists() and numa_mem_id() to point to the proper node since all cpus are now online. So the prerequisite for CONFIG_HAVE_MEMORYLESS_NODES is that there is an arch-specific set_numa_mem() that makes this mapping correct like ia64 does. If that's the case, then it's (1) completely undocumented and (2) Nishanth's patch is incomplete because anything that adds CONFIG_HAVE_MEMORYLESS_NODES needs to do the proper set_numa_mem() for it to be any different than numa_node_id(). -- 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>