sched: Prevent unnecessary active balance of single task in sched group

[firefly-linux-kernel-4.4.55.git] / kernel / sched / fair.c

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 56362ac036b23976fe616013a1fb3f66f2f23213..2dc28766cf9a3ab3c0b00ba4089b8aeda635f7f3 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5650,6 +5650,7 @@ struct lb_env {
        int                     new_dst_cpu;
        enum cpu_idle_type      idle;
        long                    imbalance;
+       unsigned int            src_grp_nr_running;
        /* The set of CPUs under consideration for load-balancing */
        struct cpumask          *cpus;
 
@@ -6612,6 +6613,8 @@ next_group:
        if (env->sd->flags & SD_NUMA)
                env->fbq_type = fbq_classify_group(&sds->busiest_stat);
 
+       env->src_grp_nr_running = sds->busiest_stat.sum_nr_running;
+
        if (!env->sd->parent) {
                /* update overload indicator if we are at root domain */
                if (env->dst_rq->rd->overload != overload)
@@ -7240,7 +7243,8 @@ more_balance:
                 * excessive cache_hot migrations and active balances.
                 */
                if (idle != CPU_NEWLY_IDLE)
-                       sd->nr_balance_failed++;
+                       if (env.src_grp_nr_running > 1)
+                               sd->nr_balance_failed++;
 
                if (need_active_balance(&env)) {
                        raw_spin_lock_irqsave(&busiest->lock, flags);