[PATCH 3/4] sched/core: Enable core scheduler only for core with SMT threads

[Tim Chen]

Core scheduler has extra overhead.  Enable it only for core with
more than one SMT hardware threads.

Signed-off-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
---
 kernel/sched/core.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 1a132beba3f8..9d875d6ed3f3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -280,8 +280,10 @@ static int __sched_core_stopper(void *data)
 		}
 	}
 
-	for_each_online_cpu(cpu)
-		cpu_rq(cpu)->core_enabled = enabled;
+	for_each_online_cpu(cpu) {
+		if (!enabled || (enabled && cpumask_weight(cpu_smt_mask(cpu)) >= 2))
+			cpu_rq(cpu)->core_enabled = enabled;
+	}
 
 	return 0;
 }
-- 
2.20.1