Subject: Re: [PATCH 09/11] Powerpc/smp: Create coregroup domain

From: Gautham R Shenoy <[email-masked]>
Date: Fri, 17 Jul 2020 13:53:45 +0530

On Fri, Jul 17, 2020 at 01:49:26PM +0530, Gautham R Shenoy wrote:

> > +int cpu_to_coregroup_id(int cpu)
> > +{
> > +	return cpu_to_core_id(cpu);
> > +}
> 
> 
> So, if has_coregroup_support() returns true, then since the core_group
> identification is currently done through the core-id, the
> coregroup_mask is going to be the same as the
> cpu_core_mask/cpu_cpu_mask. Thus, we will be degenerating the DIE
> domain. Right ? Instead we could have kept the core-group to be a
> single bigcore by default, so that those domains can get degenerated
> preserving the legacy SMT, DIE, NUMA hierarchy.

Never mind, got confused with core_id and cpu_core_mask (which
corresponds to the cores of a chip).  cpu_to_core_id() does exactly
what we have described above. Sorry for the noise.

I am ok with this patch, except that I would request if all the
changes to the topology structure be done within a single function for
ease of tracking it instead of distributing it all over the code.

> 
> 
> 
> 
> > +
> >  static int topology_update_init(void)
> >  {
> >  	start_topology_update();
> > -- 
> > 2.17.1
> >