Re: [Qemu-devel] [RFC] kvm: x86: export vCPU halted state to sysfs

[Eduardo Habkost]

(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 <address@hidden> 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?

-- 
Eduardo