Re: [libvirt] [RFC] phi support in libvirt
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On Mon, Dec 26, 2016 at 07:57:42PM +0800, Feng, Shaohe wrote:
for the NUMA format,
we still uses "memory" to describe the mcdram.
But we remove the cpus elements.
<numa>
<cell id='3' memory='8' unit='GiB'/> </numa>
<cell id='4' memory='8' unit='GiB'/> </numa>
At present, for this kind CPUless NUMA , we only support mcdram as memroy
backend.
Yep, that sounds ok.
<domain>
...
<memoryBacking>
<mcdram nodeset="3-4"/>
</memoryBacking>
</domain>
And we reject a CPUless NUMA without memroy backend.
Maybe we will allow it in futures after qemu can handle it well.
Yes, that's ok too.
A question:
1. Should libvirt probe the "host-nodes" for this kind of memory to make a
smart map?
The qemu arguments will be as follow:
-object
memory-backend-ram,size=8G,prealloc=yes,host-nodes=0,policy=bind,id=node3 \
-numa node,nodeid=3,memdev=node3 \
-object
memory-backend-ram,size=8G,prealloc=yes,host-nodes=0,policy=bind,id=node4 \
-numa node,nodeid=4,memdev=node4 \
2. or we let user specify the host-nodes.
<memoryBacking>
<mcdram nodeset="3-4", host-nodes="0-1"/>
</memoryBacking>
</domain>
You don't need to do that - <numatune> already lets the user say
which host node, each guest node is attached to
http://libvirt.org/formatdomain.html#elementsNUMATuning
<numatune>
<memory mode="strict" nodeset="1-4,^3"/>
<memnode cellid="0" mode="strict" nodeset="1"/>
<memnode cellid="2" mode="preferred"
nodeset="2"/>
</numatune>
Regards,
Daniel
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