On Fri, Feb 02, 2018 at 05:23:59PM +0000, Dr. David Alan Gilbert wrote:
* Eduardo Habkost (ehabkost@redhat.com) wrote:
(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@redhat.com> 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.
Would that data be available without the bql? I ask because if it is then a small advantage to having a separate command is that the command could be marked OOB with Peter's new series and never take the lock.
We would need a mechanism to safely walk the CPU list without the BQL, so I wouldn't bother trying to make a OOB-capable version of query-cpus unless really necessary. -- Eduardo