sched/tune: Add support for negative boost values

Change-Id: I164ee04ba98c3a776605f18cb65ee61b3e917939

Contains also:

eas/stune: schedtune cpu boost_max must be non-negative.

This is to avoid under-accounting cpu capacity which may
cause task stacking and frequency spikes.

Change-Id: Ie1c1cbd52a6edb77b4c15a830030aa748dff6f29

2 files changed, 37 insertions, 25 deletions

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 2b23dfefe6f1..aef41d9acd83 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5250,22 +5250,25 @@ static bool cpu_overutilized(int cpu)
 
 #ifdef CONFIG_SCHED_TUNE
 
-static unsigned long
-schedtune_margin(unsigned long signal, unsigned long boost)
+static long
+schedtune_margin(unsigned long signal, long boost)
 {
-	unsigned long long margin = 0;
+	long long margin = 0;
 
 	/*
 	 * Signal proportional compensation (SPC)
 	 *
 	 * The Boost (B) value is used to compute a Margin (M) which is
 	 * proportional to the complement of the original Signal (S):
-	 *   M = B * (SCHED_LOAD_SCALE - S)
+	 *   M = B * (SCHED_LOAD_SCALE - S), if B is positive
+	 *   M = B * S, if B is negative
 	 * The obtained M could be used by the caller to "boost" S.
 	 */
-	margin  = SCHED_LOAD_SCALE - signal;
-	margin *= boost;
-
+	if (boost >= 0) {
+		margin  = SCHED_LOAD_SCALE - signal;
+		margin *= boost;
+	} else
+		margin = -signal * boost;
 	/*
 	 * Fast integer division by constant:
 	 *  Constant   :                 (C) = 100
@@ -5281,13 +5284,15 @@ schedtune_margin(unsigned long signal, unsigned long boost)
 	margin  *= 1311;
 	margin >>= 17;
 
+	if (boost < 0)
+		margin *= -1;
 	return margin;
 }
 
-static inline unsigned int
+static inline int
 schedtune_cpu_margin(unsigned long util, int cpu)
 {
-	unsigned int boost;
+	int boost;
 
 #ifdef CONFIG_CGROUP_SCHEDTUNE
 	boost = schedtune_cpu_boost(cpu);
@@ -5300,12 +5305,12 @@ schedtune_cpu_margin(unsigned long util, int cpu)
 	return schedtune_margin(util, boost);
 }
 
-static inline unsigned long
+static inline long
 schedtune_task_margin(struct task_struct *task)
 {
-	unsigned int boost;
+	int boost;
 	unsigned long util;
-	unsigned long margin;
+	long margin;
 
 #ifdef CONFIG_CGROUP_SCHEDTUNE
 	boost = schedtune_task_boost(task);
@@ -5323,13 +5328,13 @@ schedtune_task_margin(struct task_struct *task)
 
 #else /* CONFIG_SCHED_TUNE */
 
-static inline unsigned int
+static inline int
 schedtune_cpu_margin(unsigned long util, int cpu)
 {
 	return 0;
 }
 
-static inline unsigned int
+static inline int
 schedtune_task_margin(struct task_struct *task)
 {
 	return 0;
@@ -5341,7 +5346,7 @@ static inline unsigned long
 boosted_cpu_util(int cpu)
 {
 	unsigned long util = cpu_util(cpu);
-	unsigned long margin = schedtune_cpu_margin(util, cpu);
+	long margin = schedtune_cpu_margin(util, cpu);
 
 	trace_sched_boost_cpu(cpu, util, margin);
 
@@ -5352,7 +5357,7 @@ static inline unsigned long
 boosted_task_util(struct task_struct *task)
 {
 	unsigned long util = task_util(task);
-	unsigned long margin = schedtune_task_margin(task);
+	long margin = schedtune_task_margin(task);
 
 	trace_sched_boost_task(task, util, margin);
 
diff --git a/kernel/sched/tune.c b/kernel/sched/tune.c
index 8ca8db2de818..afc4a7747161 100644
--- a/kernel/sched/tune.c
+++ b/kernel/sched/tune.c
@@ -213,10 +213,11 @@ static struct schedtune *allocated_group[BOOSTGROUPS_COUNT] = {
  */
 struct boost_groups {
 	/* Maximum boost value for all RUNNABLE tasks on a CPU */
-	unsigned boost_max;
+	bool idle;
+	int boost_max;
 	struct {
 		/* The boost for tasks on that boost group */
-		unsigned boost;
+		int boost;
 		/* Count of RUNNABLE tasks on that boost group */
 		unsigned tasks;
 	} group[BOOSTGROUPS_COUNT];
@@ -229,7 +230,7 @@ static void
 schedtune_cpu_update(int cpu)
 {
 	struct boost_groups *bg;
-	unsigned boost_max;
+	int boost_max;
 	int idx;
 
 	bg = &per_cpu(cpu_boost_groups, cpu);
@@ -243,9 +244,13 @@ schedtune_cpu_update(int cpu)
 		 */
 		if (bg->group[idx].tasks == 0)
 			continue;
+
 		boost_max = max(boost_max, bg->group[idx].boost);
 	}
-
+	/* Ensures boost_max is non-negative when all cgroup boost values
+	 * are neagtive. Avoids under-accounting of cpu capacity which may cause
+	 * task stacking and frequency spikes.*/
+	boost_max = max(boost_max, 0);
 	bg->boost_max = boost_max;
 }
 
@@ -391,7 +396,7 @@ int schedtune_task_boost(struct task_struct *p)
 	return task_boost;
 }
 
-static u64
+static s64
 boost_read(struct cgroup_subsys_state *css, struct cftype *cft)
 {
 	struct schedtune *st = css_st(css);
@@ -401,11 +406,13 @@ boost_read(struct cgroup_subsys_state *css, struct cftype *cft)
 
 static int
 boost_write(struct cgroup_subsys_state *css, struct cftype *cft,
-	    u64 boost)
+	    s64 boost)
 {
 	struct schedtune *st = css_st(css);
+	unsigned threshold_idx;
+	int boost_pct;
 
-	if (boost < 0 || boost > 100)
+	if (boost < -100 || boost > 100)
 		return -EINVAL;
 
 	st->boost = boost;
@@ -423,8 +430,8 @@ boost_write(struct cgroup_subsys_state *css, struct cftype *cft,
 static struct cftype files[] = {
 	{
 		.name = "boost",
-		.read_u64 = boost_read,
-		.write_u64 = boost_write,
+		.read_s64 = boost_read,
+		.write_s64 = boost_write,
 	},
 	{ }	/* terminate */
 };