[libvirt] CPU topology 'sockets' handling guest vs host
On my x86_64 host I have a pair of Quad core CPUs, each in a separate
NUMA node. The virsh capabilities
topology data reports this:
# virsh capabilities | xmllint --xpath /capabilities/host/cpu -
<cpu>
<arch>x86_64</arch>
<model>Opteron_G3</model>
<vendor>AMD</vendor>
<topology sockets="1" cores="4" threads="1"/>
<feature name="osvw"/>
<feature name="3dnowprefetch"/>
<feature name="cr8legacy"/>
<feature name="extapic"/>
<feature name="cmp_legacy"/>
<feature name="3dnow"/>
<feature name="3dnowext"/>
<feature name="pdpe1gb"/>
<feature name="fxsr_opt"/>
<feature name="mmxext"/>
<feature name="ht"/>
<feature name="vme"/>
</cpu>
# virsh capabilities | xmllint --xpath /capabilities/host/topology -
<topology>
<cells num="2">
<cell id="0">
<cpus num="4">
<cpu id="0"/>
<cpu id="1"/>
<cpu id="2"/>
<cpu id="3"/>
</cpus>
</cell>
<cell id="1">
<cpus num="4">
<cpu id="4"/>
<cpu id="5"/>
<cpu id="6"/>
<cpu id="7"/>
</cpus>
</cell>
</cells>
</topology>
Note, it is reporting sockets=1, because sockets is the number of sockets
*per* NUMA node.
Now I try to figure the guest to match the host using:
<cpu>
<topology sockets='1' cores='4' threads='1'/>
<numa>
<cell cpus='0-3' memory='512000'/>
<cell cpus='4-7' memory='512000'/>
</numa>
</cpu>
And I get:
error: Maximum CPUs greater than topology limit
So, the XML checker is mistaking 'sockets' as the total number of sockets,
rather than the per-node socket count. We need to fix this bogus check
Daniel
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