Re: [patch 2/2] enables booting a NUMA system where some nodes have no memory

Martin J. Bligh
2006-11-16T15:51:22Z

Christian Krafft wrote:
> On Wed, 15 Nov 2006 16:57:56 -0800 (PST)
> Christoph Lameter <clameter@sgi.com> wrote:
>
>> On Thu, 16 Nov 2006, KAMEZAWA Hiroyuki wrote:
>>
>>>> But there is no memory on the node. Does the zonelist contain the zones of
>>>> the node without memory or not? We simply fall back each allocation to the
>>>> next node as if the node was overflowing?
>>> yes. just fallback.
>> Ok, so we got a useless pglist_data struct and the struct zone contains a
>> zonelist that does not include the zone.
>
> Okay, I slowly understand what you are talking about.
> I just tried a "numactl --cpunodebind 1 --membind 1 true" which hit an uninitialized zone in slab_node:
>
> return zone_to_nid(policy->v.zonelist->zones[0]);
>
> I also still don't know if it makes sense to have memoryless nodes, but supporting it does.
> So wath would be reasonable, to have empty zonelists for those node, or to check if zonelists are uninitialized ?

You don't want empty zonelists on a node containing CPUs, else it won't
know where to allocate from. You just want to make sure that the zones
in that node (if existant) are not contained in *anyone's* zonelist.

M.