Re: [RFC][PATCH] node hotplug : register_cpu() changes [0/3]

From: KAMEZAWA Hiroyuki
Date: Tue May 23 2006 - 20:16:54 EST

On Tue, 23 May 2006 07:52:03 -0700
Ashok Raj <ashok.raj@xxxxxxxxx> wrote:

> On Tue, May 23, 2006 at 07:56:36PM +0900, KAMEZAWA Hiroyuki wrote:
> > I found acpi container, which describes node, could evaluate cpu before
> > memory. This means cpu-hot-add occurs before memory hot add.
> >
> Is it possible to process memory before cpu in container hot-add code?

Maybe No. I know ACPI people doesn't want to add special handling for cpu/memory
in a container. It complicates the code very much.

> > In most part, cpu-hot-add doesn't depend on node hot add.
> > But register_cpu, which creates symbolic link from node to cpu, requires
> Dont you need all per-cpu allocated on that node? Or is it from node0 or
> something for all hotpluggable cpus?
I want to allocate on-node. But it's impossible now because per-cpu-pages
has to be allocated at boot-time as for possible cpus. They has to be
off-node now. They are from node0 (ia64) now.

I want to migrate per-cpu when a cpu is enabled (if I can). But maybe there
is a code which has pointer to object in per-cpu area.

> If node is online first, then all allocations come from that node, thought you
> *want* to ensure node/mem is online before cpu is up to get that benefit.
Yes. But per-cpu should be allocated at boot-time now. I'd like to go step-by-step.


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