On Fri, 2 Feb 2018 16:49:54 -0500 Luiz Capitulino <lcapitulino@redhat.com> wrote:
On Fri, 2 Feb 2018 18:41:44 -0200 Eduardo Habkost <ehabkost@redhat.com> wrote:
On Fri, Feb 02, 2018 at 03:19:45PM -0500, Luiz Capitulino wrote:
On Fri, 2 Feb 2018 18:09:12 -0200 Eduardo Habkost <ehabkost@redhat.com> wrote: [...]
Your plan above covers what will happen when using newer QEMU versions, but libvirt still needs to work sanely if running QEMU 2.11. My suggestion is that libvirt do not run query-cpus to ask for the "halted" field on any architecture except s390.
My current plan is to ask libvirt to completely remove query-cpus usage, independent of the arch and use the new command instead.
This would be a regression for people running QEMU 2.11 on s390.
libvirt could use query-cpus on s390 if the new command is not available.
Btw, even on s390 query-cpus runs run_on_cpu(), which is what causes vCPUs to go to user-space. So, s390 should suffer the same performance problem. Pick your regression.
(But maybe it would be an acceptable regression? Viktor, what do you think? Are there production releases of management systems that already rely on vcpu.<n>.halted?)