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

From
Hoan Tran OS <hoan@os.amperecomputing.com>
Date
2019-07-15 17:55:26
Also in
linux-arm-kernel, linux-mm, linux-s390, lkml, sparclinux
Reply to
Michal Hocko, 2019-07-12
Hi,

On 7/12/19 10:00 PM, Michal Hocko wrote:
On Fri 12-07-19 15:37:30, Will Deacon wrote:
quoted
Hi all,

On Fri, Jul 12, 2019 at 02:12:23PM +0200, Michal Hocko wrote:
quoted
On Fri 12-07-19 10:56:47, Hoan Tran OS wrote:
[...]
quoted
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/ (local)

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!
Thread (29 messages) 29 messages, 8 authors, last reply 2019-09-02
Keyboard shortcuts
hback out one level
jnext message in thread / next series-diff position
kprevious message in thread / previous series-diff position
ldrill in
Escclose help / fold thread tree
?toggle this help