* Eric Blake (ebl...@redhat.com) wrote:
> On 05/12/2017 08:31 AM, Alexey Perevalov wrote:
> > Right now it could be used on destination side to
> > enable vCPU blocktime calculation for postcopy live migration.
> > vCPU blocktime - it's time since vCPU thread was put into
> > interruptible sleep, till memory page was copied and thread awake.
> >
> > Signed-off-by: Alexey Perevalov <a.pereva...@samsung.com>
> > ---
> > include/migration/migration.h | 1 +
> > migration/migration.c | 9 +++++++++
> > qapi-schema.json | 5 ++++-
> > 3 files changed, 14 insertions(+), 1 deletion(-)
> >
>
> > +++ b/qapi-schema.json
> > @@ -894,11 +894,14 @@
> > # @release-ram: if enabled, qemu will free the migrated ram pages on the
> > source
> > # during postcopy-ram migration. (since 2.9)
> > #
> > +# @postcopy-blocktime: Calculate downtime for postcopy live migration
> > (since 2.10)
> > +#
> > # Since: 1.2
> > ##
> > { 'enum': 'MigrationCapability',
> > 'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',
> > - 'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram'] }
> > + 'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram',
> > + 'postcopy-blocktime'] }
>
> Why does this need to be a capability that we have to turn on, and not
> something that is collected unconditionally? Is there a drawback to
> having the stat collection always enabled without a capability?
Yes, there was a reasonable CPU/memory overhead.
(Although it might be lower now).
Dave
> --
> Eric Blake, Principal Software Engineer
> Red Hat, Inc. +1-919-301-3266
> Virtualization: qemu.org | libvirt.org
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
