The following commit has been merged into the sched/core branch of tip:

Commit-ID:     9a5e22fbb0c88bff33458ede98b0fa922fab3831
Gitweb:        https://git.kernel.org/tip/9a5e22fbb0c88bff33458ede98b0fa922fab3831
Author:        Tim Chen <tim.c.chen@linux.intel.com>
AuthorDate:    Wed, 01 Apr 2026 14:52:23 -07:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Thu, 09 Apr 2026 15:49:50 +02:00

sched/cache: Check local_group only once in update_sg_lb_stats()

There is no need to check the local group twice for both
group_asym_packing and group_smt_balance. Adjust the code
to facilitate future checks for group types (cache-aware
load balancing) as well.

No functional changes are expected.

Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Co-developed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/99a57865c8ae1847087a5c00e92d24351cf3e5a8.1775065312.git.tim.c.chen@linux.intel.com
---
 kernel/sched/fair.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index cea625c..d3812d1 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -11385,14 +11385,16 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 
 	sgs->group_weight = group->group_weight;
 
-	/* Check if dst CPU is idle and preferred to this group */
-	if (!local_group && env->idle && sgs->sum_h_nr_running &&
-	    sched_group_asym(env, sgs, group))
-		sgs->group_asym_packing = 1;
-
-	/* Check for loaded SMT group to be balanced to dst CPU */
-	if (!local_group && smt_balance(env, sgs, group))
-		sgs->group_smt_balance = 1;
+	if (!local_group) {
+		/* Check if dst CPU is idle and preferred to this group */
+		if (env->idle && sgs->sum_h_nr_running &&
+		    sched_group_asym(env, sgs, group))
+			sgs->group_asym_packing = 1;
+
+		/* Check for loaded SMT group to be balanced to dst CPU */
+		if (smt_balance(env, sgs, group))
+			sgs->group_smt_balance = 1;
+	}
 
 	sgs->group_type = group_classify(env->sd->imbalance_pct, group, sgs);