Re: [RFC:Patch: 000/008](memory hotplug) rough idea of pgdat removing

[Christoph Lameter]

Yasunori Goto wrote:

> Current my idea is using RCU feature for waiting them.
> Because it is the least impact against reader's performance,
> and pgdat remover can wait finish of reader's access to pgdat
> which is removing by synchronize_sched().

The use of RCU disables preemption which has implications as to what can be done in a loop over nodes or zones. This would also potentially add more overhead to the page allocator hotpaths.


> If you have better idea, please let me know.

Use stop_machine()? The removal of a zone or node is a pretty rare event after all and it would avoid having to deal with rcu etc etc.

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