[PATCH v2 4/7] sched/fair: Introduce sched_smt_siblings_idle()

[Ricardo Neri]

Architectures that implement arch_asym_cpu_priority() may need to know the
idle state of the SMT siblings of a CPU. The scheduler has this information
and functionality. Expose it.

Move the existing functionality outside of the NUMA code.

Cc: Ben Segall <bsegall@xxxxxxxxxx>
Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
Cc: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
Cc: Len Brown <len.brown@xxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Cc: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Tim C. Chen <tim.c.chen@xxxxxxxxx>
Cc: Valentin Schneider <vschneid@xxxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@xxxxxxxxxxxxxxx>
---
Changes since v1:
 * Introduced this patch.
---
 include/linux/sched.h |  2 ++
 kernel/sched/fair.c   | 39 ++++++++++++++++++++++-----------------
 2 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index ffb6eb55cd13..0d01c64ac737 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2426,4 +2426,6 @@ static inline void sched_core_fork(struct task_struct *p) { }
 
 extern void sched_set_stop_task(int cpu, struct task_struct *stop);
 
+extern bool sched_smt_siblings_idle(int cpu);
+
 #endif
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 0e4251f83807..9517c48df50e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1052,6 +1052,28 @@ update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
  * Scheduling class queueing methods:
  */
 
+static inline bool is_core_idle(int cpu)
+{
+#ifdef CONFIG_SCHED_SMT
+	int sibling;
+
+	for_each_cpu(sibling, cpu_smt_mask(cpu)) {
+		if (cpu == sibling)
+			continue;
+
+		if (!idle_cpu(sibling))
+			return false;
+	}
+#endif
+
+	return true;
+}
+
+bool sched_smt_siblings_idle(int cpu)
+{
+	return is_core_idle(cpu);
+}
+
 #ifdef CONFIG_NUMA
 #define NUMA_IMBALANCE_MIN 2
 
@@ -1691,23 +1713,6 @@ struct numa_stats {
 	int idle_cpu;
 };
 
-static inline bool is_core_idle(int cpu)
-{
-#ifdef CONFIG_SCHED_SMT
-	int sibling;
-
-	for_each_cpu(sibling, cpu_smt_mask(cpu)) {
-		if (cpu == sibling)
-			continue;
-
-		if (!idle_cpu(sibling))
-			return false;
-	}
-#endif
-
-	return true;
-}
-
 struct task_numa_env {
 	struct task_struct *p;
 
-- 
2.25.1