Re: [RFC PATCH 1/2] powerpc/numa: fix cpu_to_node() usage during boot

On 15.07.2015 [16:35:16 -0400], Tejun Heo wrote:

Hello,

On Thu, Jul 02, 2015 at 04:02:02PM -0700, Nishanth Aravamudan wrote:

quoted

we currently emit at boot:

[    0.000000] pcpu-alloc: [0] 0 1 2 3 [0] 4 5 6 7 

After this commit, we correctly emit:

[    0.000000] pcpu-alloc: [0] 0 1 2 3 [1] 4 5 6 7 

JFYI, the numbers in the brackets aren't NUMA node numbers but percpu
allocation group numbers and they're not split according to nodes but
percpu allocation units.  In both cases, there are two units each
serving 0-3 and 4-7.  In the above case, because it wasn't being fed
the correct NUMA information, both got assigned to the same group.  In
the latter, they got assigned to different ones but even then if the
group numbers match NUMA node numbers, that's just a coincidence.

Ok, thank you for clarifying! From a correctness perspective, even if
the numbers don't match NUMA nodes, should we expect the grouping to be
split along NUMA topology?

-Nish