sched/fair: Do not compute NUMA Balancing stats unnecessarily during lb

Aggregate nr_numa_running and nr_preferred_running when load balancing
at NUMA domains only. While at it, also move the aggregation below the
idle_cpu() check since an idle CPU cannot have any preferred tasks.

Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20241223043407.1611-7-kprateek.nayak@amd.com

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 52f72784e95397ffbb7bd6b9f272c86ac599e85c..650d698244c473fddfd0dfddd25c0a68811dde66 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -10409,7 +10409,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
                                      bool *sg_overloaded,
                                      bool *sg_overutilized)
 {
-       int i, nr_running, local_group;
+       int i, nr_running, local_group, sd_flags = env->sd->flags;
 
        memset(sgs, 0, sizeof(*sgs));
 
@@ -10433,10 +10433,6 @@ static inline void update_sg_lb_stats(struct lb_env *env,
                if (cpu_overutilized(i))
                        *sg_overutilized = 1;
 
-#ifdef CONFIG_NUMA_BALANCING
-               sgs->nr_numa_running += rq->nr_numa_running;
-               sgs->nr_preferred_running += rq->nr_preferred_running;
-#endif
                /*
                 * No need to call idle_cpu() if nr_running is not 0
                 */
@@ -10446,10 +10442,17 @@ static inline void update_sg_lb_stats(struct lb_env *env,
                        continue;
                }
 
+#ifdef CONFIG_NUMA_BALANCING
+               /* Only fbq_classify_group() uses this to classify NUMA groups */
+               if (sd_flags & SD_NUMA) {
+                       sgs->nr_numa_running += rq->nr_numa_running;
+                       sgs->nr_preferred_running += rq->nr_preferred_running;
+               }
+#endif
                if (local_group)
                        continue;
 
-               if (env->sd->flags & SD_ASYM_CPUCAPACITY) {
+               if (sd_flags & SD_ASYM_CPUCAPACITY) {
                        /* Check for a misfit task on the cpu */
                        if (sgs->group_misfit_task_load < rq->misfit_task_load) {
                                sgs->group_misfit_task_load = rq->misfit_task_load;