On 13.02.2014 [14:41:04 -0800], David Rientjes wrote: > 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(). I'm working on this latter bit now. I tried to mirror ia64, but it looks like they have CONFIG_USER_PERCPU_NUMA_NODE_ID, which powerpc doesn't. It seems like CONFIG_USER_PERCPU_NUMA_NODE_ID and CONFIG_HAVE_MEMORYLESS_NODES should be tied together in Kconfig? I'll keep working, but would appreciate any further insight. -Nish -- 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>