[PATCH 2/4] sched/topology: all instances of a sched group must use the same sched_group_capacity

From: Lauro Ramos Venancio
Date: Thu Apr 20 2017 - 15:52:47 EST


Use the group balance cpu to select the same sched_group_capacity
instance for all instances of a sched group.

As the group mask is stored in the struct sched_group_capacity and the
function group_balance_cpu() cannot be used when the group mask is not
available, this patch creates a function to find the group balance cpu
when the mask is not available.

Signed-off-by: Lauro Ramos Venancio <lvenanci@xxxxxxxxxx>
---
kernel/sched/topology.c | 26 ++++++++++++++++++++++++--
1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index f8b53b3..55bbaf7 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -529,6 +529,27 @@ int group_balance_cpu(struct sched_group *sg)
return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
}

+/*
+ * Find the group balance cpu when the group mask is not available yet.
+ */
+static int find_group_balance_cpu(struct sched_domain *sd,
+ struct sched_group *sg)
+{
+ const struct cpumask *sg_span = sched_group_cpus(sg);
+ struct sd_data *sdd = sd->private;
+ struct sched_domain *sibling;
+ int i;
+
+ for_each_cpu(i, sg_span) {
+ sibling = *per_cpu_ptr(sdd->sd, i);
+ if (cpumask_test_cpu(i, sched_domain_span(sibling)))
+ return i;
+ }
+
+ WARN(1, "group balance cpu not found.");
+ return 0;
+}
+
static struct sched_group *
build_group_from_child_sched_domain(struct sched_domain *sd, int cpu)
{
@@ -551,10 +572,11 @@ int group_balance_cpu(struct sched_group *sg)
}

static void init_overlap_sched_group(struct sched_domain *sd,
- struct sched_group *sg, int cpu)
+ struct sched_group *sg)
{
struct sd_data *sdd = sd->private;
struct cpumask *sg_span;
+ int cpu = find_group_balance_cpu(sd, sg);

sg->sgc = *per_cpu_ptr(sdd->sgc, cpu);
if (atomic_inc_return(&sg->sgc->ref) == 1)
@@ -601,7 +623,7 @@ static void init_overlap_sched_group(struct sched_domain *sd,
sg_span = sched_group_cpus(sg);
cpumask_or(covered, covered, sg_span);

- init_overlap_sched_group(sd, sg, i);
+ init_overlap_sched_group(sd, sg);

if (!first)
first = sg;
--
1.8.3.1