Re: [Qemu-devel] [Qemu-ppc] [PATCH qemu] spapr_pci: Add numa node id

[David Gibson]

On Thu, Sep 22, 2016 at 02:49:34PM +1000, David Gibson wrote:
> On Wed, Sep 14, 2016 at 07:03:50AM -0500, Michael Roth wrote:
> > Quoting Alexey Kardashevskiy (2016-09-14 04:39:10)
> > > On 14/09/16 09:29, Michael Roth wrote:
> > > > Quoting Alexey Kardashevskiy (2016-07-27 03:03:38)
> > > >> This adds a numa id property to a PHB to allow linking passed PCI 
> > > >> device
> > > >> to CPU/memory. It is up to the management stack to do CPU/memory 
> > > >> pinning
> > > >> to the node with the actual PCI device.
> > > > 
> > > > It looks like x86 relies on PCIBus->numa_node() method (via
> > > > pci_bus_numa_node()) to encode similar PCIBus affinities
> > > > into ACPI tables, and currently exposes it via
> > > > -device pci-[-express]-expander-bus,numa_node=X.
> > > 
> > > 
> > > 
> > > Well, until we allow DMA windows per PCI bus (not per PHB as it is now),
> > > this won't make much sense for us (unless I am missing something here).
> > 
> > I didn't consider that it's not a bus-level setting; I think
> > you're right that re-using the interface to both store/retrieve doesn't
> > make much sense in that case.
> > 
> > My thought that was that since pci_bus_numa_node() could in theory come
> > to be relied upon by common PCI code, that we should use it as well. But
> > even if it doesn't make sense for us to use it, wouldn't it make sense to
> > still set PCIBus->numa_node (in addition to the PHB-wide value) in the
> > off-chance that common code does come to rely on
> > pci_bus_numa_node()?
> 
> Yes, it would be a good idea to set the PCIBus node value to inherit
> the one that's set for the host bridge, just in case any generic code
> looks at it in future.

But that can be a followup patch, I've applied this to ppc-for-2.8
now.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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