From 16d364ba6ef2aa59b409df70682770f3ed23f7c0 Mon Sep 17 00:00:00 2001 From: Ricardo Neri Date: Fri, 10 Sep 2021 18:18:15 -0700 Subject: sched/topology: Introduce sched_group::flags There exist situations in which the load balance needs to know the properties of the CPUs in a scheduling group. When using asymmetric packing, for instance, the load balancer needs to know not only the state of dst_cpu but also of its SMT siblings, if any. Use the flags of the child scheduling domains to initialize scheduling group flags. This will reflect the properties of the CPUs in the group. A subsequent changeset will make use of these new flags. No functional changes are introduced. Originally-by: Peter Zijlstra (Intel) Signed-off-by: Ricardo Neri Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Joel Fernandes (Google) Reviewed-by: Len Brown Reviewed-by: Vincent Guittot Link: https://lkml.kernel.org/r/20210911011819.12184-3-ricardo.neri-calderon@linux.intel.com --- kernel/sched/topology.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) (limited to 'kernel/sched/topology.c') diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 4e8698e62f07..c56faae461d9 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -716,8 +716,20 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) tmp = sd; sd = sd->parent; destroy_sched_domain(tmp); - if (sd) + if (sd) { + struct sched_group *sg = sd->groups; + + /* + * sched groups hold the flags of the child sched + * domain for convenience. Clear such flags since + * the child is being destroyed. + */ + do { + sg->flags = 0; + } while (sg != sd->groups); + sd->child = NULL; + } } for (tmp = sd; tmp; tmp = tmp->parent) @@ -916,10 +928,12 @@ build_group_from_child_sched_domain(struct sched_domain *sd, int cpu) return NULL; sg_span = sched_group_span(sg); - if (sd->child) + if (sd->child) { cpumask_copy(sg_span, sched_domain_span(sd->child)); - else + sg->flags = sd->child->flags; + } else { cpumask_copy(sg_span, sched_domain_span(sd)); + } atomic_inc(&sg->ref); return sg; @@ -1169,6 +1183,7 @@ static struct sched_group *get_group(int cpu, struct sd_data *sdd) if (child) { cpumask_copy(sched_group_span(sg), sched_domain_span(child)); cpumask_copy(group_balance_mask(sg), sched_group_span(sg)); + sg->flags = child->flags; } else { cpumask_set_cpu(cpu, sched_group_span(sg)); cpumask_set_cpu(cpu, group_balance_mask(sg)); -- cgit v1.2.3-59-g8ed1b