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

[Shivaprasad G Bhat]

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