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SubjectRe: [Patch 2/2]: powerpc/hotplug/mm: Fix hot-add memory node assoc
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I am running into this problem on PowerPC systems where Balbir's patch set
was targeted. So, yes, I do need to be able to add/enable a new numa node
during system execution in cases where more resources (memory, virtual
processors) are added to the system dynamically.

On 05/25/2017 10:46 PM, Michael Ellerman wrote:
> Reza Arbab <arbab@linux.vnet.ibm.com> writes:
>
>> On Thu, May 25, 2017 at 04:19:53PM +1000, Michael Ellerman wrote:
>>> The commit message for 3af229f2071f says:
>>>
>>> In practice, we never see a system with 256 NUMA nodes, and in fact, we
>>> do not support node hotplug on power in the first place, so the nodes
>>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>> that are online when we come up are the nodes that will be present for
>>> the lifetime of this kernel.
>>>
>>> Is that no longer true?
>>
>> I don't know what the reasoning behind that statement was at the time,
>> but as far as I can tell, the only thing missing for node hotplug now is
>> Balbir's patchset [1]. He fixes the resource issue which motivated
>> 3af229f2071f and reverts it.
>>
>> With that set, I can instantiate a new numa node just by doing
>> add_memory(nid, ...) where nid doesn't currently exist.
>
> But does that actually happen on any real system?
>
> cheers
>
>

--
Michael W. Bringmann
Linux Technology Center
IBM Corporation
Tie-Line 363-5196
External: (512) 286-5196
Cell: (512) 466-0650
mwb@linux.vnet.ibm.com

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