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

[Ashok Raj <ashok.raj@intel.com>]

On Wed, May 24, 2006 at 09:18:15AM +0900, KAMEZAWA Hiroyuki wrote:
> On Tue, 23 May 2006 07:52:03 -0700
> Ashok Raj <ashok.raj@intel.com> 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.

Iam not attached to the API change, so disassociating the node from cpu is ok.
It just feels a bit weird to say node is not online. 

Probably ACPI doesnt give a precise way to put the dependencies (in a certain
order), there are EDL/EJD, but they have limitations and not directly imply
a dependency like this. But container code having to deal with this dependency
for add/remove is probably ok. 

i hope container would eventually perform onlining the pieces from user space
scripts via udev like mechanisms.

I remember folks from SGI posting patches to cpu only nodes in the past. 
Same way there are probably IO only nodes. Are you sure we cover these cases 
as well.
> 
> > > 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?
> > 

-- 
Cheers,
Ashok Raj
- Open Source Technology Center