Re: [RFC PATCH] dt:numa: adding numa node mapping for memory nodes.

[Hanjun Guo <hanjun.guo@linaro.org>]

On 2014-9-18 3:34, Mark Rutland wrote:
> On Wed, Sep 17, 2014 at 04:37:30PM +0100, Kumar Gala wrote:
>>
>> On Sep 17, 2014, at 1:56 AM, Ganapatrao Kulkarni <ganapatrao.kulkarni@caviumnetworks.com> wrote:
>>
>>> From: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
>>>
>>> This patch adds property "nid" to memory node to provide the memory range to
>>> numa node id mapping.
>>>
>>> Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
>>>
>>> —
>>
>> Adding the PPC guys as they’ve been doing NUMA on IBM Power Servers
>> for years with OF/DT.  So we should really try and follow what they’ve
>> done.
> 
> Agreed.
> 
>>> Documentation/devicetree/bindings/numa.txt | 58 ++++++++++++++++++++++++++++++
>>> 1 file changed, 58 insertions(+)
>>> create mode 100644 Documentation/devicetree/bindings/numa.txt
>>>
>>> diff --git a/Documentation/devicetree/bindings/numa.txt b/Documentation/devicetree/bindings/numa.txt
>>> new file mode 100644
>>> index 0000000..c4a94f2
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/numa.txt
>>> @@ -0,0 +1,58 @@
>>> +======================================================
>>> +numa id binding description
>>> +======================================================
>>> +
>>> +======================================================
>>> +1 - Introduction
>>> +======================================================
>>> +The device node  property "nid(numa node id)" can be added to memory
> 
> Why the quotes?
> 
>>> +device node to map the range of memory addresses as defined in property "reg".
>>> +The property "nid" maps the memory range to the numa node id, which is used to
>>> +find the local and remory pages on numa aware systems.
> 
> What is a "numa node id", exactly, and how is the OS intended to use it?

I think "Proximity Domain" would be more suitably, processors and memory or IOs
in the same domain will have better performance than crossing other domains.

Thanks
Hanjun