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SubjectRe: [Question or BUG] [NUMA]: I feel puzzled at the function cpumask_of_node
[CC linux-api]

On Wed 07-06-17 17:23:20, Leizhen (ThunderTown) wrote:
> When I executed numactl -H(print cpumask_of_node for each node), I got
> different result on X86 and ARM64. For each numa node, the former
> only displayed online CPUs, and the latter displayed all possible
> CPUs. Actually, all other ARCHs is the same to ARM64.
>
> So, my question is: Which case(online or possible) should function
> cpumask_of_node be? Or there is no matter about it?

Unfortunatelly the documentation is quite unclear
What: /sys/devices/system/node/nodeX/cpumap
Date: October 2002
Contact: Linux Memory Management list <linux-mm@kvack.org>
Description:
The node's cpumap.

not really helpeful, is it? Semantically I _think_ printing online cpus
makes more sense because it doesn't really make much sense to bind
anything on offline nodes. Generic implementtion of cpumask_of_node
indeed provides only online cpus. I haven't checked specific
implementations of arch specific code but listing offline cpus sounds
confusing to me.

--
Michal Hocko
SUSE Labs

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