Re: [PATCH v8 1/7] x86, memhp, numa: Online memory-less nodes at boot time.

From: Tejun Heo
Date: Tue Jul 19 2016 - 14:50:30 EST


On Tue, Jul 19, 2016 at 03:28:02PM +0800, Dou Liyang wrote:
> In this series of patches, we are going to construct cpu <-> node mapping
> for all possible cpus at boot time, which is a 1-1 mapping. It means the

1-1 mapping means that each cpu is mapped to its own private node
which isn't the case. Just call it a persistent mapping?

> cpu will be mapped to the node it belongs to, and will never be changed.
> If a node has only cpus but no memory, the cpus on it will be mapped to
> a memory-less node. And the memory-less node should be onlined.
> This patch allocate pgdats for all memory-less nodes and online them at
> boot time. Then build zonelists for these nodes. As a result, when cpus
> on these memory-less nodes try to allocate memory from local node, it
> will automatically fall back to the proper zones in the zonelists.

Yeah, I think this is an a lot better approach for memory-less nodes.

> Signed-off-by: Zhu Guihua <zhugh.fnst@xxxxxxxxxxxxxx>
> Signed-off-by: Dou Liyang <douly.fnst@xxxxxxxxxxxxxx>

Acked-by: Tejun Heo <tj@xxxxxxxxxx>