Re: [RFC PATCH] sched/topology: Introduce NUMA identity node sched domain

[Suravee Suthikulpanit]

On 8/11/17 11:57, Suravee Suthikulpanit wrote:
> > > [...]
> > > @@ -1445,9 +1448,24 @@ void sched_init_numa(void)
> > >          tl[i] = sched_domain_topology[i];
> > >
> > >      /*
> > > +     * Ignore the NUMA identity level if it has the same cpumask
> > > +     * as previous level. This is the case for:
> > > +     *   - System with last-level-cache (MC) sched domain span a NUMA node.
> > > +     *   - System with DIE sched domain span a NUMA node.
> > > +     *
> > > +     * Assume all NUMA nodes are identical, so only check node 0.
> > > +     */
> > > +    if (!cpumask_equal(sched_domains_numa_masks[0][0], tl[i-1].mask(0)))
> > > +        tl[i++] = (struct sched_domain_topology_level){
> > > +            .mask = sd_numa_mask,
> > > +            .numa_level = 0,
> > > +            SD_INIT_NAME(NODE)
> > > +        };
> >
> > So what you've forgotten to mention is that for those systems where the
> > LLC == NODE this now superfluous level gets removed by the degenerate
> > code. Have you verified that does the right thing?
>
> Let me check with that one and get back.

Actually, it is not removed by the degenerate code. That is what this logic is 
for. It checks for LCC == NODE or DIE == NODE before setting up the NODE sched 
level. I can update the comment. This has also been tested on system w/ LLC == NODE.

Thanks,
Suravee