Re: [PATCH v2 0/5] mm: Enable CONFIG_NODES_SPAN_OTHER_NODES by default for NUMA

[Will Deacon]

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.

Will