Messages in this thread | | | Date | Mon, 12 Jul 2021 18:18:56 +0530 | From | Srikar Dronamraju <> | Subject | Re: [PATCH v2 1/2] sched/topology: Skip updating masks for non-online nodes |
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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
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