Re: [2/8,v3] NUMA Hotplug Emulator: infrastructure of NUMA hotplug emulation

Shaohui Zheng
2010-11-18T06:49:00Z

On Thu, Nov 18, 2010 at 03:27:15PM +0900, Paul Mundt wrote:
> On Thu, Nov 18, 2010 at 12:14:07PM +0800, Shaohui Zheng wrote:
> > On Wed, Nov 17, 2010 at 01:10:50PM -0800, David Rientjes wrote:
> > > The idea that I've proposed (and you've apparently thought about and even
> > > implemented at one point) is much more powerful than that. We need not
> > > query the state of hidden nodes that we've setup at boot but can rather
> > > use the amount of hidden memory to setup the nodes in any way that we want
> > > at runtime (various sizes, interleaved node ids, etc).
> >
> > yes, if we select your proposal. we just mark all the nodes as POSSIBLE node.
> > there is no hidden nodes any more. the node will be created after add memory
> > to the node first time.
> >
> This is roughly what I had in mind in my N_HIDDEN review, so I quite
> favour this approach.

Our testing shows that it is a feasible approach, and it works well.
however, there is still a problem which we should worry about.

in our draft patch, we re-setup nr_node_ids when CONFIG_ARCH_MEMORY_PROBE enabled
and mem=XXX was specified in grub. we set nr_node_ids as MAX_NUMNODES + 1, because
we do not know how many nodes will be hot-added through memory/probe interface.
it might be a little wasting of memory.

--
Thanks & Regards,
Shaohui