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

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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

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