anolis: sched: don't account util_est for each cfs_rq when group_balancer disabled

ANBZ: #8765

If we account util_est for each cfs_rq when group_balancer disabled,
there will be some overhead. To avoid the overhead, we only account it
when group balancer enabled, and when the switch is turned, we
recalculate for each cfs_rq at once.

Signed-off-by: Cruz Zhao <CruzZhao@linux.alibaba.com>
Reviewed-by: Tianchen Ding <dtcccc@linux.alibaba.com>
Link: https://gitee.com/anolis/cloud-kernel/pulls/5529

kernel/sched/core.c

@@ -99,10 +99,17 @@ static void group_balancer_enable(void)
 {
 	sched_init_group_balancer_sched_domains();
 	static_branch_enable(&__group_balancer_enabled);
+	/*
+	 * Ensure all previous instances of raw_spin_rq_*lock() have finished
+	 * and future ones will observe group_balancer_enabled().
+	 */
+	synchronize_rcu();
+	util_est_reenqueue_all();
 }
 
 static void group_balancer_disable(void)
 {
+	util_est_clear_all();
 	static_branch_disable(&__group_balancer_enabled);
 	sched_clear_group_balancer_sched_domains();
 }
@@ -112,6 +119,11 @@ bool group_balancer_enabled(void)
 	return static_branch_unlikely(&__group_balancer_enabled);
 }
 
+bool group_balancer_rq_enabled(struct rq *rq)
+{
+	return static_branch_unlikely(&__group_balancer_enabled) && rq->group_balancer_enabled;
+}
+
 int sched_group_balancer_enable_handler(struct ctl_table *table, int write,
 					void __user *buffer, size_t *lenp, loff_t *ppos)
 {

kernel/sched/fair.c

@@ -6038,6 +6038,64 @@ static inline void util_est_dequeue(struct cfs_rq *cfs_rq,
 	trace_sched_util_est_cfs_tp(cfs_rq);
 }
 
+#ifdef CONFIG_GROUP_BALANCER
+void util_est_reenqueue_all(void)
+{
+	int cpu;
+	struct rq *rq;
+	struct rq_flags rf;
+	struct cfs_rq *cfs_rq;
+	struct sched_entity *se;
+	struct task_struct *p;
+
+	cpus_read_lock();
+	for_each_online_cpu(cpu) {
+		rq = cpu_rq(cpu);
+		rq_lock_irqsave(rq, &rf);
+		list_for_each_entry(p, &rq->cfs_tasks, se.group_node) {
+			se = &p->se;
+			for_each_sched_entity(se) {
+				cfs_rq = cfs_rq_of(se);
+				if (cfs_rq != &rq->cfs)
+					util_est_enqueue(cfs_rq, p);
+			}
+		}
+		rq->group_balancer_enabled = true;
+		rq_unlock_irqrestore(rq, &rf);
+	}
+	cpus_read_unlock();
+}
+
+static int tg_util_est_clear_down(struct task_group *tg, void *data)
+{
+	int cpu;
+	struct rq *rq;
+	struct rq_flags rf;
+	struct cfs_rq *cfs_rq;
+
+	if (tg == &root_task_group)
+		return 0;
+
+	cpus_read_lock();
+	for_each_online_cpu(cpu) {
+		rq = cpu_rq(cpu);
+		cfs_rq = tg->cfs_rq[cpu];
+		rq_lock_irqsave(rq, &rf);
+		WRITE_ONCE(cfs_rq->avg.util_est.enqueued, 0);
+		rq->group_balancer_enabled = false;
+		rq_unlock_irqrestore(rq, &rf);
+	}
+	cpus_read_unlock();
+
+	return 0;
+}
+
+void util_est_clear_all(void)
+{
+	walk_tg_tree_from(&root_task_group, tg_util_est_clear_down, tg_nop, NULL);
+}
+#endif
+
 #define UTIL_EST_MARGIN (SCHED_CAPACITY_SCALE / 100)
 
 /*
@@ -8221,12 +8279,15 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 	 * Let's add the task's estimated utilization to the cfs_rq's
 	 * estimated utilization, before we update schedutil.
 	 */
+	if (group_balancer_rq_enabled(rq)) {
 		for_each_sched_entity(se) {
 			cfs_rq = cfs_rq_of(se);
 			util_est_enqueue(cfs_rq, p);
 		}
-
 		se = &p->se;
+	} else {
+		util_est_enqueue(&rq->cfs, p);
+	}
 
 	/*
 	 * If in_iowait is set, the code below may not trigger any cpufreq
@@ -8351,12 +8412,15 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 	int idle_h_nr_running = task_has_idle_policy(p);
 	bool was_sched_idle = sched_idle_rq(rq);
 
+	if (group_balancer_rq_enabled(rq)) {
 		for_each_sched_entity(se) {
 			cfs_rq = cfs_rq_of(se);
 			util_est_dequeue(cfs_rq, p);
 		}
-
 		se = &p->se;
+	} else {
+		util_est_dequeue(&rq->cfs, p);
+	}
 
 	for_each_sched_entity(se) {
 		cfs_rq = cfs_rq_of(se);

kernel/sched/sched.h

@@ -1542,6 +1542,7 @@ struct rq {
 
 #ifdef CONFIG_GROUP_BALANCER
 	struct group_balancer_sched_domain *gb_sd;
+	bool			group_balancer_enabled;
 #endif
 
 	CK_KABI_RESERVE(1)
@@ -3705,6 +3706,7 @@ extern void sched_dynamic_update(int mode);
 
 #ifdef CONFIG_GROUP_BALANCER
 extern bool group_balancer_enabled(void);
+extern bool group_balancer_rq_enabled(struct rq *rq);
 static inline const struct cpumask *task_allowed_cpu(struct task_struct *p)
 {
 	if (group_balancer_enabled()) {
@@ -3746,7 +3748,10 @@ extern unsigned long cfs_h_load(struct cfs_rq *cfs_rq);
 extern bool gb_cpu_overutilized(int cpu);
 extern void gb_load_balance(struct lb_env *env);
 extern void task_tick_gb(struct task_struct *p);
+extern void util_est_reenqueue_all(void);
+extern void util_est_clear_all(void);
 #else
+static inline bool group_balancer_rq_enabled(struct rq *rq) { return false; }
 static inline const struct cpumask *task_allowed_cpu(struct task_struct *p)
 {
 	return p->cpus_ptr;