Re: [PATCH v3 14/14] vdpa: Add x-svq to NetdevVhostVDPAOptions

[Eugenio Perez Martin]

On Thu, Mar 3, 2022 at 7:09 AM Markus Armbruster <armbru@redhat.com> wrote:
>
> Eugenio Pérez <eperezma@redhat.com> writes:
>
> > Finally offering the possibility to enable SVQ from the command line.
> >
> > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > ---
> >  qapi/net.json    |  5 ++++-
> >  net/vhost-vdpa.c | 48 ++++++++++++++++++++++++++++++++++++++++--------
> >  2 files changed, 44 insertions(+), 9 deletions(-)
> >
> > diff --git a/qapi/net.json b/qapi/net.json
> > index 7fab2e7cd8..d243701527 100644
> > --- a/qapi/net.json
> > +++ b/qapi/net.json
> > @@ -445,12 +445,15 @@
> >  # @queues: number of queues to be created for multiqueue vhost-vdpa
> >  #          (default: 1)
> >  #
> > +# @x-svq: Start device with (experimental) shadow virtqueue. (Since 7.0)
> > +#
> >  # Since: 5.1
> >  ##
> >  { 'struct': 'NetdevVhostVDPAOptions',
> >    'data': {
> >      '*vhostdev':     'str',
> > -    '*queues':       'int' } }
> > +    '*queues':       'int',
> > +    '*x-svqs':        'bool' } }
>
> Experimental members *must* be tagged with feature @unstable.  Their
> name *may* start with 'x-' to help human users, at the cost of renames
> when the member becomes stable.
>

Hi Markus,

Thank you very much for the warning. I'll add the unstable feature tag.

If I understood correctly this needs to be done as x-perf at
BackupCommon struct. Could you confirm to me that it marks only the
x-perf member as unstable? Without reading the actual comment it might
seem as if it marks all the whole BackupCommon struct as unstable.

# ...
# @filter-node-name: the node name that should be assigned to the
#                    filter driver that the backup job inserts into the graph
#                    above node specified by @drive. If this option is
not given,
#                    a node name is autogenerated. (Since: 4.2)
#
# @x-perf: Performance options. (Since 6.0)
#
# Features:
# @unstable: Member @x-perf is experimental.
#
# Note: @on-source-error and @on-target-error only affect background
#       I/O.  If an error occurs during a guest write request, the device's
#       rerror/werror actions will be used.
#
# Since: 4.2
##
{ 'struct': 'BackupCommon',
  'data': { ...
            '*filter-node-name': 'str',
            '*x-perf': { 'type': 'BackupPerf',
                         'features': [ 'unstable' ] } } }