Re: [PATCH 0/3] KVM-userspace: add NUMA support for guests

[Avi Kivity <avi@redhat.com>]

Andre Przywara wrote:
> The user (or better: management application) specifies the host nodes
> the guest should use: -nodes 2,3 would create a two node guest mapped to
> node 2 and 3 on the host. These numbers are handed over to libnuma:
> VCPUs are pinned to the nodes and the allocated guest memory is bound to
> it's respective node. Since libnuma seems not to be installed
> everywhere, the user has to enable this via configure --enable-numa
> In the BIOS code an ACPI SRAT table was added, which describes the NUMA
> topology to the guest. The number of nodes is communicated via the CMOS
> RAM (offset 0x3E). If someone thinks of this as a bad idea, tell me.

There exists now a firmware interface in qemu for this kind of 
communications.

> To take use of the new BIOS, install the iasl compiler
> (http://acpica.org/downloads/) and type "make bios" before installing,
> so the default BIOS will be replaced with the modified one.
> Node over-committing is allowed (-nodes 0,0,0,0), omitting the -nodes
> parameter reverts to the old behavior.

'-nodes' is too generic a name ('node' could also mean a host).  Suggest 
-numanode.

Need more flexibility: specify the range of memory per node, which cpus 
are in the node, relative weights for the SRAT table:

   -numanode node=1,cpu=2,cpu=3,start=1G,size=1G,hostnode=3

Also need a monitor command to change host nodes dynamically:

(qemu) numanode 1 0


-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.