Hi, On 7/12/19 10:00 PM, Michal Hocko wrote: > On Fri 12-07-19 15:37:30, Will Deacon wrote: >> Hi all, >> >> On Fri, Jul 12, 2019 at 02:12:23PM +0200, Michal Hocko wrote: >>> On Fri 12-07-19 10:56:47, Hoan Tran OS wrote: >>> [...] >>>> It would be good if we can enable it by-default. Otherwise, let arch >>>> enables it by them-self. Do you have any suggestions? >>> >>> I can hardly make any suggestions when it is not really clear _why_ you >>> want to remove this config option in the first place. Please explain >>> what motivated you to make this change. >> >> Sorry, I think this confusion might actually be my fault and Hoan has just >> been implementing my vague suggestion here: >> >> https://lore.kernel.org/linux-arm-kernel/20190625101245.s4vxfosoop52gl4e@willie-the-truck/ >> >> If the preference of the mm folks is to leave CONFIG_NODES_SPAN_OTHER_NODES >> as it is, then we can define it for arm64. I just find it a bit weird that >> the majority of NUMA-capable architectures have to add a symbol in the arch >> Kconfig file, for what appears to be a performance optimisation applicable >> only to ia64, mips and sh. >> >> At the very least we could make the thing selectable. > > Hmm, I thought this was selectable. But I am obviously wrong here. > Looking more closely, it seems that this is indeed only about > __early_pfn_to_nid and as such not something that should add a config > symbol. This should have been called out in the changelog though. Yes, do you have any other comments about my patch? > > Also while at it, does HAVE_MEMBLOCK_NODE_MAP fall into a similar > bucket? Do we have any NUMA architecture that doesn't enable it? > As I checked with arch Kconfig files, there are 2 architectures, riscv and microblaze, do not support NUMA but enable this config. And 1 architecture, alpha, supports NUMA but does not enable this config. Thanks and Regards Hoan > Thanks! >
