[Patch v4 11/22] sched/cache: Check local_group only once in update_sg_lb_stats()

Tim Chen
2026-04-01T21:46:59Z

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>
---

Notes:
v3->v4:
No change.

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 62a628a1594c..4ed84086244c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -11228,14 +11228,16 @@ 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);

--
2.32.0