* Nathan Lynch <nath...@linux.ibm.com> [2019-08-22 12:17:48]:
> Hi Srikar,
Thanks Nathan for the review.
>
> > However home node associativity requires cpu's hwid which is set in
> > smp_setup_pacas. Hence call smp_setup_pacas before numa_setup_cpus.
>
> But this seems like it would negatively affect pacas' NUMA placements?
>
> Would it be less risky to figure out a way to do "early" VPHN hcalls
> before mem_topology_setup, getting the hwids from the cpu_to_phys_id
> array perhaps?
>
Do you mean for calls from mem_topology_setup(), stuff we use cpu_to_phys_id
but for the calls from ppc_numa_cpu_prepare() we use the
get_hard_smp_processor_id()?
Thats doable.
>
> > diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> > index 88b5157..7965d3b 100644
> > --- a/arch/powerpc/mm/numa.c
> > +++ b/arch/powerpc/mm/numa.c
> > @@ -461,6 +461,21 @@ static int of_drconf_to_nid_single(struct drmem_lmb
> > *lmb)
> > return nid;
> > }
> >
> > +static int vphn_get_nid(unsigned long cpu)
> > +{
> > + __be32 associativity[VPHN_ASSOC_BUFSIZE] = {0};
> > + long rc;
> > +
> > + /* Use associativity from first thread for all siblings */
>
> I don't understand how this comment corresponds to the code it
> accompanies.
Okay will rephrase
>
>
> > + rc = hcall_vphn(get_hard_smp_processor_id(cpu),
> > + VPHN_FLAG_VCPU, associativity);
> > +
> > + if (rc == H_SUCCESS)
> > + return associativity_to_nid(associativity);
> ^^ extra space
>
> > @@ -490,7 +505,18 @@ static int numa_setup_cpu(unsigned long lcpu)
> > goto out;
> > }
> >
> > - nid = of_node_to_nid_single(cpu);
> > + /*
> > + * On a shared lpar, the device tree might not have the correct node
> > + * associativity. At this time lppaca, or its __old_status field
>
> Sorry but I'm going to quibble with this phrasing a bit. On SPLPAR the
> CPU nodes have no affinity information in the device tree at all. This
> comment implies that they may have incorrect information, which is
> AFAIK not the case.
>
Okay will clarify.
--
Thanks and Regards
Srikar Dronamraju
