[libvirt] [PATCH 2/2] qemu: Enable NUMA node tag in pci-root for PPC64

[Shivaprasad G Bhat]

Hi Daniel,

Can we have this patch for now ? Or should it come along with 
multiple-phb support ?

Thanks,
Shivaprasad

On 11/08/2016 07:40 PM, Shivaprasad G Bhat wrote:
>
>
> On 11/08/2016 05:59 PM, Daniel P. Berrange wrote:
>> That doesn't really solve the bug above properly - your solution here
>> only works if all the PCI devices (whether emulated or host-assigned)
>> are to be associated with the same guest NUMA node. This is a pretty
>> restrictive setup and so of limited use IMHO.
>
> Yes. It is restrictive. There can be no 1:1 pinning of host to guest 
> nodes. But, one can have multiple host nodes pinned to 1 guest node 
> which the host bridge is pinned to.
>
> This helps only to the extent that, the guest drivers wont find -1 in 
> the sysfs/numa_node. Some drivers are known to crash when they find 
> -1. The patch addresses that part of the problem.
>
>> It seems like to solve this requires that we create multiple PCI Host
>> Bridges ?
>
> Yes. That will be the actual fix to have 1:1 pinning. The current 
> approach keeps that in mind and we can have the numa_node attribute 
> set at the indivudual spapr-pci-host-bridge level when we have it. 
> Then, the individual <pci-root id=X> can have different target node as 
> I have in this patch.
>
> Thanks,
> Shivaprasad
>> Daniel