[openstack-dev] [nova] The libvirt.cpu_mode and libvirt.cpu_model

Jiang, Yunhong yunhong.jiang at intel.com
Wed Jan 28 22:10:29 UTC 2015

Hi, Daniel
	I recently tried the libvirt.cpu_mode and libvirt.cpu_model when I was working on cpu_info related code and found bug https://bugs.launchpad.net/nova/+bug/1412994 .  The reason is because with these two flags, all guests launched on the host will use them, while when host report back the compute capability, they report the real-hardware compute capability, instead of the compute capabilities masked by these two configs.

	I think the key thing is, these two flags are per-instance properties instead of per-host properties. 

	If we do want to keep it as per-host property, libvirt driver should return the capabilities that has been altered by these two items, but the problem is, I checked libvirt doc and seems we can't get the cpu_info for the custom cpu_mode.

	How about remove these two config items? And I don't think we should present cpu_mode/model option to end user, instead, we should only expose the feature request like disable/force some cpu_features, and the libvirt driver select the cpu_mode/model based on user's feature requirement.

	Your opinion?


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