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authorRicardo Neri <ricardo.neri-calderon@linux.intel.com>2021-09-10 18:18:15 -0700
committerPeter Zijlstra <peterz@infradead.org>2021-10-05 15:52:00 +0200
commit16d364ba6ef2aa59b409df70682770f3ed23f7c0 (patch)
tree6a78f989176e245e8a0d0e7bcda4cf1111b8ba46 /kernel/sched
parent183b8ec38f1ec6c1f8419375303bf1d09a2b8369 (diff)
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) <peterz@infradead.org> Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Reviewed-by: Len Brown <len.brown@intel.com> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org> Link: https://lkml.kernel.org/r/20210911011819.12184-3-ricardo.neri-calderon@linux.intel.com
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/sched.h1
-rw-r--r--kernel/sched/topology.c21
2 files changed, 19 insertions, 3 deletions
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 198058bb54d7..e5c4d4ddd83a 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1808,6 +1808,7 @@ struct sched_group {
unsigned int group_weight;
struct sched_group_capacity *sgc;
int asym_prefer_cpu; /* CPU of highest priority in group */
+ int flags;
/*
* The CPUs this group covers.
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));