Re: [libvirt] [RFC] kvm: x86: export vCPU halted state to sysfs

(CCing qemu-devel) On Fri, Feb 02, 2018 at 09:21:59AM -0500, Luiz Capitulino wrote: > On Fri, 2 Feb 2018 14:19:38 +0000 > Daniel P. Berrangé <berrange(a)redhat.com&gt; wrote: >> On Fri, Feb 02, 2018 at 12:15:54PM -0200, Eduardo Habkost wrote: [...] >>> It would be also interesting to update QEMU QMP documentation to >>> clarify the arch-specific semantics of "halted". >> >> Any also especially clarify the awful performance implications of running >> this particular query command. In general I would not expect query-xxx >> monitor commands to interrupt all vcpus, so we should clearly warn about >> this ! > > Or deprecate it... We could deprecate the expensive fields on query-cpus, and move them to a more expensive query-cpu-state command. I believe most users of query-cpus are only interested in qom_path, thread_id, and topology info. Markus, Eric: from the QAPI point of view, is it OK to remove fields between QEMU versions, as long as we follow our deprecation policy?