Merge "sched: walt: take runnable into account for placement descision"

kernel/sched/walt/trace.h

@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * Copyright (c) 2019-2021, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
  */
 
 #undef TRACE_SYSTEM
@@ -1091,11 +1092,13 @@ TRACE_EVENT(sched_find_best_target,
 		 unsigned long candidates,
 		 int most_spare_cap,
 		 int order_index, int end_index,
-		 int skip, bool running),
+		 int skip, bool running,
+		 int most_spare_rq_cpu, unsigned int cpu_rq_runnable_cnt),
 
 	TP_ARGS(tsk, min_util, start_cpu, candidates,
 		most_spare_cap,
-		order_index, end_index, skip, running),
+		order_index, end_index, skip, running,
+		most_spare_rq_cpu, cpu_rq_runnable_cnt),
 
 	TP_STRUCT__entry(
 		__array(char,		comm, TASK_COMM_LEN)
@@ -1108,6 +1111,8 @@ TRACE_EVENT(sched_find_best_target,
 		__field(int,		end_index)
 		__field(int,		skip)
 		__field(bool,		running)
+		__field(int,		most_spare_rq_cpu)
+		__field(unsigned int,	cpu_rq_runnable_cnt)
 		),
 
 	TP_fast_assign(
@@ -1121,9 +1126,11 @@ TRACE_EVENT(sched_find_best_target,
 		__entry->end_index	= end_index;
 		__entry->skip		= skip;
 		__entry->running	= running;
+		__entry->most_spare_rq_cpu	= most_spare_rq_cpu;
+		__entry->cpu_rq_runnable_cnt	= cpu_rq_runnable_cnt;
 		),
 
-	TP_printk("pid=%d comm=%s start_cpu=%d candidates=%#lx most_spare_cap=%d order_index=%d end_index=%d skip=%d running=%d",
+	TP_printk("pid=%d comm=%s start_cpu=%d candidates=%#lx most_spare_cap=%d order_index=%d end_index=%d skip=%d running=%d min_util=%lu spare_rq_cpu=%d min_runnable=%u",
 		  __entry->pid, __entry->comm,
 		  __entry->start_cpu,
 		  __entry->candidates,
@@ -1131,7 +1138,10 @@ TRACE_EVENT(sched_find_best_target,
 		  __entry->order_index,
 		  __entry->end_index,
 		  __entry->skip,
-		  __entry->running)
+		  __entry->running,
+		  __entry->min_util,
+		  __entry->most_spare_rq_cpu,
+		  __entry->cpu_rq_runnable_cnt)
 );
 
 TRACE_EVENT(sched_enq_deq_task,

kernel/sched/walt/walt_cfs.c

@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (c) 2020-2021, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
  */
 
 #include <trace/hooks/sched.h>
@@ -227,6 +228,8 @@ static inline bool is_complex_sibling_idle(int cpu)
 }
 
 static inline int walt_get_mvp_task_prio(struct task_struct *p);
+
+#define DIRE_STRAITS_PREV_NR_LIMIT 10
 static void walt_find_best_target(struct sched_domain *sd,
 					cpumask_t *candidates,
 					struct task_struct *p,
@@ -239,8 +242,9 @@ static void walt_find_best_target(struct sched_domain *sd,
 	int i, start_cpu;
 	long spare_wake_cap, most_spare_wake_cap = 0;
 	int most_spare_cap_cpu = -1;
+	int least_nr_cpu = -1;
+	unsigned int cpu_rq_runnable_cnt = UINT_MAX;
 	int prev_cpu = task_cpu(p);
-	int active_candidate = -1;
 	int order_index = fbt_env->order_index, end_index = fbt_env->end_index;
 	int stop_index = INT_MAX;
 	int cluster;
@@ -305,9 +309,6 @@ static void walt_find_best_target(struct sched_domain *sd,
 			if (!cpu_active(i))
 				continue;
 
-			if (active_candidate == -1)
-				active_candidate = i;
-
 			/*
 			 * This CPU is the target of an active migration that's
 			 * yet to complete. Avoid placing another task on it.
@@ -340,6 +341,16 @@ static void walt_find_best_target(struct sched_domain *sd,
 				most_spare_cap_cpu = i;
 			}
 
+			/*
+			 * Keep track of runnables for each CPU, if none of the
+			 * CPUs have spare capacity then use CPU with less
+			 * number of runnables.
+			 */
+			if (cpu_rq(i)->nr_running < cpu_rq_runnable_cnt) {
+				cpu_rq_runnable_cnt = cpu_rq(i)->nr_running;
+				least_nr_cpu = i;
+			}
+
 			/*
 			 * Ensure minimum capacity to grant the required boost.
 			 * The target CPU can be already at a capacity level higher
@@ -451,21 +462,26 @@ static void walt_find_best_target(struct sched_domain *sd,
 	 * We have set idle or target as long as they are valid CPUs.
 	 * If we don't find either, then we fallback to most_spare_cap,
 	 * If we don't find most spare cap, we fallback to prev_cpu,
-	 * provided that the prev_cpu is active.
-	 * If the prev_cpu is not active, we fallback to active_candidate.
+	 * provided that the prev_cpu is active and has less than
+	 * DIRE_STRAITS_PREV_NR_LIMIT runnables otherwise, we fallback to cpu
+	 * with least number of runnables.
 	 */
 
 	if (unlikely(cpumask_empty(candidates))) {
 		if (most_spare_cap_cpu != -1)
 			cpumask_set_cpu(most_spare_cap_cpu, candidates);
-		else if (!cpu_active(prev_cpu) && active_candidate != -1)
-			cpumask_set_cpu(active_candidate, candidates);
+		else if (cpu_active(prev_cpu)
+			 && (cpu_rq(prev_cpu)->nr_running < DIRE_STRAITS_PREV_NR_LIMIT))
+			cpumask_set_cpu(prev_cpu, candidates);
+		else if (least_nr_cpu != -1)
+			cpumask_set_cpu(least_nr_cpu, candidates);
 	}
 
 out:
 	trace_sched_find_best_target(p, min_task_util, start_cpu, cpumask_bits(candidates)[0],
 			     most_spare_cap_cpu, order_index, end_index,
-			     fbt_env->skip_cpu, task_on_rq_queued(p));
+			     fbt_env->skip_cpu, task_on_rq_queued(p), least_nr_cpu,
+			     cpu_rq_runnable_cnt);
 }
 
 static inline unsigned long