Hi Valentin,
> On 01/07/21 09:45, Srikar Dronamraju wrote:
> > @@ -1891,12 +1894,30 @@ void sched_init_numa(void)
> > void sched_domains_numa_masks_set(unsigned int cpu)
> > {
>
> Hmph, so we're playing games with masks of offline nodes - is that really
> necessary? Your modification of sched_init_numa() still scans all of the
> nodes (regardless of their online status) to build the distance map, and
> that is never updated (sched_init_numa() is pretty much an __init
> function).
>
> So AFAICT this is all to cope with topology_span_sane() not applying
> 'cpu_map' to its masks. That seemed fine to me back when I wrote it, but in
> light of having bogus distance values for offline nodes, not so much...
>
> What about the below instead?
>
> ---
> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> index b77ad49dc14f..c2d9caad4aa6 100644
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -2075,6 +2075,7 @@ static struct sched_domain *build_sched_domain(struct
> sched_domain_topology_leve
> static bool topology_span_sane(struct sched_domain_topology_level *tl,
> const struct cpumask *cpu_map, int cpu)
> {
> + struct cpumask *intersect = sched_domains_tmpmask;
> int i;
>
> /* NUMA levels are allowed to overlap */
> @@ -2090,14 +2091,17 @@ static bool topology_span_sane(struct
> sched_domain_topology_level *tl,
> for_each_cpu(i, cpu_map) {
> if (i == cpu)
> continue;
> +
> /*
> - * We should 'and' all those masks with 'cpu_map' to exactly
> - * match the topology we're about to build, but that can only
> - * remove CPUs, which only lessens our ability to detect
> - * overlaps
> + * We shouldn't have to bother with cpu_map here, unfortunately
> + * some architectures (powerpc says hello) have to deal with
> + * offline NUMA nodes reporting bogus distance values. This can
> + * lead to funky NODE domain spans, but since those are offline
> + * we can mask them out.
> */
> + cpumask_and(intersect, tl->mask(cpu), tl->mask(i));
> if (!cpumask_equal(tl->mask(cpu), tl->mask(i)) &&
> - cpumask_intersects(tl->mask(cpu), tl->mask(i)))
> + cpumask_intersects(intersect, cpu_map))
> return false;
> }
>
Unfortunately this is not helping.
I tried this patch alone and also with 2/2 patch of this series where
we update/fill fake topology numbers. However both cases are still failing.
--
Thanks and Regards
Srikar Dronamraju
