On 07/11/2014 08:33 AM, Greg KH wrote: > On Fri, Jul 11, 2014 at 10:29:56AM +0200, Peter Zijlstra wrote: >> > On Fri, Jul 11, 2014 at 03:37:17PM +0800, Jiang Liu wrote: >>> > > Any comments are welcomed! >> > >> > Why would anybody _ever_ have a memoryless node? That's ridiculous. > I'm with Peter here, why would this be a situation that we should even > support? Are there machines out there shipping like this? This is orthogonal to the problem Jiang Liu is solving, but... The IBM guys have been hitting the CPU-less and memoryless node issues forever, but that's mostly because their (traditional) hypervisor had good NUMA support and ran multi-node guests. I've never seen it in practice on x86 mostly because the hypervisors don't have good NUMA support. I honestly think this is something x86 is going to have to handle eventually anyway. It's essentially a resource fragmentation problem, and there are going to be times where a guest needs to be spun up and hypervisor has nodes with either no spare memory or no spare CPUs. The hypervisor has 3 choices in this case: 1. Lie about the NUMA layout 2. Waste the resources 3. Tell the guest how it's actually arranged -- To unsubscribe from this list: send the line "unsubscribe linux-hotplug" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
