Re: [PATCH 02/10] numa: introduce MachineClass::forbid_asymmetrical_numa

[Eduardo Habkost]

On Thu, Aug 20, 2020 at 11:17:26AM +1000, David Gibson wrote:
> On Fri, Aug 14, 2020 at 05:54:16PM -0300, Daniel Henrique Barboza wrote:
> > The pSeries machine does not support asymmetrical NUMA
> > configurations.
> 
> This seems a bit oddly specific to have as a global machine class
> property.
> 
> Would it make more sense for machines with specific NUMA constraints
> to just verify those during their initialization?

This would be much simpler.  However, I like the idea of
representing machine-specific configuration validation rules as
data that can eventually be exported to management software.

(CCing John Snow, who had spent some time thinking about
configuration validation recently.)


> > 
> > CC: Eduardo Habkost <ehabkost@redhat.com>
> > CC: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
> > Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
> > ---
> >  hw/core/numa.c      | 7 +++++++
> >  hw/ppc/spapr.c      | 1 +
> >  include/hw/boards.h | 1 +
> >  3 files changed, 9 insertions(+)
> > 
> > diff --git a/hw/core/numa.c b/hw/core/numa.c
> > index d1a94a14f8..1e81233c1d 100644
> > --- a/hw/core/numa.c
> > +++ b/hw/core/numa.c
> > @@ -547,6 +547,7 @@ static int parse_numa(void *opaque, QemuOpts *opts, 
> > Error **errp)
> >   */
> >  static void validate_numa_distance(MachineState *ms)
> >  {
> > +    MachineClass *mc = MACHINE_GET_CLASS(ms);
> >      int src, dst;
> >      bool is_asymmetrical = false;
> >      int nb_numa_nodes = ms->numa_state->num_nodes;
> > @@ -575,6 +576,12 @@ static void validate_numa_distance(MachineState *ms)
> >      }
> >  
> >      if (is_asymmetrical) {
> > +        if (mc->forbid_asymmetrical_numa) {
> > +            error_report("This machine type does not support "
> > +                         "asymmetrical numa distances.");
> > +            exit(EXIT_FAILURE);
> > +        }
> > +
> >          for (src = 0; src < nb_numa_nodes; src++) {
> >              for (dst = 0; dst < nb_numa_nodes; dst++) {
> >                  if (src != dst && numa_info[src].distance[dst] == 0) {
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index dd2fa4826b..3b16edaf4c 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -4512,6 +4512,7 @@ static void spapr_machine_class_init(ObjectClass *oc, 
> > void *data)
> >       */
> >      mc->numa_mem_align_shift = 28;
> >      mc->auto_enable_numa = true;
> > +    mc->forbid_asymmetrical_numa = true;
> >  
> >      smc->default_caps.caps[SPAPR_CAP_HTM] = SPAPR_CAP_OFF;
> >      smc->default_caps.caps[SPAPR_CAP_VSX] = SPAPR_CAP_ON;
> > diff --git a/include/hw/boards.h b/include/hw/boards.h
> > index bc5b82ad20..dc6cdd1c53 100644
> > --- a/include/hw/boards.h
> > +++ b/include/hw/boards.h
> > @@ -215,6 +215,7 @@ struct MachineClass {
> >      bool nvdimm_supported;
> >      bool numa_mem_supported;
> >      bool auto_enable_numa;
> > +    bool forbid_asymmetrical_numa;
> >      const char *default_ram_id;
> >  
> >      HotplugHandler *(*get_hotplug_handler)(MachineState *machine,
> 
> -- 
> David Gibson                  | I'll have my music baroque, and my code
> david AT gibson.dropbear.id.au        | minimalist, thank you.  NOT _the_ 
> _other_
>                               | _way_ _around_!
> http://www.ozlabs.org/~dgibson



-- 
Eduardo