(2012/11/14 18:44:44), Daniel P. Berrange wrote:
Now, qemu guest's default cpu model is qemu32/64 and it can be configured per domain. In some case, host-model mode is suitable for getting enough performance in the guest because of features from cpu spec.
This patch adds a config option to qemu.conf to use 'host-model' mode as default and allow users to use host-model mode in domains on a host. This is useful because - Guest owners don't need to touch their domain's config. - An administrator can reduce an item in their checklist for VM performance and guarantee all guests should run in the best
On Wed, Nov 14, 2012 at 03:10:48AM +0000, Ichikawa, Ken wrote: performance.
While I understand the benefits, I'm afraid I have to NACK this at this time because using host-model doesn't really work when trying to use nested-KVM. Until we have a solution for that, we neeed to stick with a CPU model that works everywhere, since users like OpenStack do actually use nested-KVM for testing work and already complained about this when I made OpenStack set the host-model by default.
Thank you for noticing the nested-KVM problem. However, to enable this patch's function, users need to edit qemu.conf. So, if users use nested-KVM, they just don't edit the conf file. Is there still any problem? Ken ICHIKAWA