WIP: sched/fair: add boosted CPU usage

The CPU usage signal is used by EAS as an estimation of the overall currently
bandwidth allocated on a CPU. When SchedDVFS is in use, this signal affects
the selection of the operating points (OPP) required to accommodate all the
workload allocated in a CPU.
A convenient way to boost the performances of the tasks running on a CPU,
which is also little intrusive, is to boost the CPU usage signal each time
it is used to select an OPP.

This patch introduces a new function:
  get_boosted_cpu_usage(cpu)
to returns a boosted value for the usage of a specified CPU.
The margin added to the original usage is:
  1. computed by the boosting strategy introduced by a previous patch
  2. proportional to the system-wide boost value defined by the sysctl
     interface, this one also introduced by a previous patch

The boosted signal is used by SchedDVFS transparently each time it requires
to get an estimation of the capacity required for a CPU.

Change-Id: I4a3612c7ceddb8b68a1896d05ff3407cb5bf8141
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>

1 files changed, 50 insertions, 6 deletions

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ebb7ae487775..21c7bd31524f 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4265,6 +4265,7 @@ static unsigned int capacity_margin = 1280; /* ~20% margin */
 
 static bool cpu_overutilized(int cpu);
 static unsigned long get_cpu_usage(int cpu);
+static inline unsigned long get_boosted_cpu_usage(int cpu);
 struct static_key __sched_energy_freq __read_mostly = STATIC_KEY_INIT_FALSE;
 
 /*
@@ -4327,7 +4328,8 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 		 * further increases.
 		 */
 		if (sched_energy_freq() && (task_new || task_wakeup)) {
-			unsigned long req_cap = get_cpu_usage(cpu_of(rq));
+			unsigned long req_cap =
+				get_boosted_cpu_usage(cpu_of(rq));
 
 			req_cap = req_cap * capacity_margin
 					>> SCHED_CAPACITY_SHIFT;
@@ -4405,7 +4407,8 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 		 * further increases.
 		 */
 		if (sched_energy_freq() && task_sleep) {
-			unsigned long req_cap = get_cpu_usage(cpu_of(rq));
+			unsigned long req_cap =
+				get_boosted_cpu_usage(cpu_of(rq));
 
 			if (rq->cfs.nr_running) {
 				req_cap = req_cap * capacity_margin
@@ -5343,6 +5346,45 @@ static inline bool task_fits_cpu(struct task_struct *p, int cpu)
 	return __task_fits(p, cpu, get_cpu_usage(cpu));
 }
 
+#ifdef CONFIG_SCHED_TUNE
+
+static inline unsigned int
+schedtune_cpu_margin(unsigned long usage)
+{
+	unsigned int boost;
+	unsigned long margin;
+
+	boost = get_sysctl_sched_cfs_boost();
+	if (boost == 0)
+		return 0;
+	margin = schedtune_margin(usage, boost);
+
+	return margin;
+}
+
+#else /* CONFIG_SCHED_TUNE */
+
+static inline unsigned int
+schedtune_cpu_margin(unsigned long usage)
+{
+	return 0;
+}
+
+#endif /* CONFIG_SCHED_TUNE */
+
+static inline unsigned long
+get_boosted_cpu_usage(int cpu)
+{
+	unsigned long usage;
+	unsigned long margin;
+
+	usage = get_cpu_usage(cpu);
+	margin = schedtune_cpu_margin(usage);
+
+	usage += margin;
+	return usage;
+}
+
 /*
  * find_idlest_group finds and returns the least busy CPU group within the
  * domain.
@@ -7941,7 +7983,8 @@ more_balance:
 		 * tasks.
 		 */
 		if (sched_energy_freq() && cur_ld_moved) {
-			unsigned long req_cap = get_cpu_usage(env.src_cpu);
+			unsigned long req_cap =
+				get_boosted_cpu_usage(env.src_cpu);
 
 			req_cap = req_cap * capacity_margin
 					>> SCHED_CAPACITY_SHIFT;
@@ -7970,7 +8013,7 @@ more_balance:
 			 */
 			if (sched_energy_freq()) {
 				unsigned long req_cap =
-					get_cpu_usage(env.dst_cpu);
+					get_boosted_cpu_usage(env.dst_cpu);
 
 				req_cap = req_cap * capacity_margin
 						>> SCHED_CAPACITY_SHIFT;
@@ -8343,7 +8386,7 @@ static int active_load_balance_cpu_stop(void *data)
 			 */
 			if (sched_energy_freq()) {
 				unsigned long req_cap =
-					get_cpu_usage(env.src_cpu);
+					get_boosted_cpu_usage(env.src_cpu);
 
 				req_cap = req_cap * capacity_margin
 						>> SCHED_CAPACITY_SHIFT;
@@ -8368,7 +8411,8 @@ out_unlock:
 		 * further increases.
 		 */
 		if (sched_energy_freq()) {
-			unsigned long req_cap = get_cpu_usage(target_cpu);
+			unsigned long req_cap =
+				get_boosted_cpu_usage(target_cpu);
 
 			req_cap = req_cap * capacity_margin
 					>> SCHED_CAPACITY_SHIFT;