sched/tune: Add initial support for Dynamic SchedTune Boost

Provide functions to activate and reset SchedTune boost:

int do_stune_boost(char *st_name, int boost);
int reset_stune_boost(char *st_name);

Signed-off-by: joshuous <joshuous@gmail.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>

include/linux/sched.h

@@ -3283,4 +3283,9 @@ struct cpu_cycle_counter_cb {
 };
 int register_cpu_cycle_counter_cb(struct cpu_cycle_counter_cb *cb);
 
+#ifdef CONFIG_DYNAMIC_STUNE_BOOST
+int do_stune_boost(char *st_name, int boost);
+int reset_stune_boost(char *st_name);
+#endif /* CONFIG_DYNAMIC_STUNE_BOOST */
+
 #endif

init/Kconfig

@@ -1020,6 +1020,15 @@ config CGROUP_SCHEDTUNE
 
 	  Say N if unsure.
 
+config DYNAMIC_STUNE_BOOST
+	bool "Dynamic SchedTune boosting support"
+	depends on SCHED_TUNE
+	help
+	  This option extends the SchedTune framework and provides APIs to
+	  activate and reset SchedTune boosting from anywhere in the kernel.
+
+	  If unsure, say N.
+
 config MEMCG
 	bool "Memory Resource Controller for Control Groups"
 	depends on RESOURCE_COUNTERS

kernel/sched/tune.c

@@ -19,6 +19,12 @@ int sysctl_sched_cfs_boost __read_mostly;
 
 extern struct target_nrg schedtune_target_nrg;
 
+#ifdef CONFIG_DYNAMIC_STUNE_BOOST
+static DEFINE_MUTEX(stune_boost_mutex);
+static struct schedtune *getSchedtune(char *st_name);
+static int dynamic_boost_write(struct schedtune *st, int boost);
+#endif /* CONFIG_DYNAMIC_STUNE_BOOST */
+
 /* Performance Boost region (B) threshold params */
 static int perf_boost_idx;
 
@@ -129,6 +135,14 @@ struct schedtune {
 	/* Hint to bias scheduling of tasks on that SchedTune CGroup
 	 * towards idle CPUs */
 	int prefer_idle;
+
+#ifdef CONFIG_DYNAMIC_STUNE_BOOST
+	/*
+	 * This tracks the default boost value and is used to restore
+	 * the value when Dynamic SchedTune Boost is reset.
+	 */
+	int boost_default;
+#endif /* CONFIG_DYNAMIC_STUNE_BOOST */
 };
 
 static inline struct schedtune *css_st(struct cgroup_subsys_state *css)
@@ -161,6 +175,9 @@ root_schedtune = {
 	.perf_boost_idx = 0,
 	.perf_constrain_idx = 0,
 	.prefer_idle = 0,
+#ifdef CONFIG_DYNAMIC_STUNE_BOOST
+	.boost_default = 0,
+#endif /* CONFIG_DYNAMIC_STUNE_BOOST */
 };
 
 int
@@ -598,6 +615,9 @@ boost_write(struct cgroup_subsys_state *css, struct cftype *cft,
 	st->perf_constrain_idx = threshold_idx;
 
 	st->boost = boost;
+#ifdef CONFIG_DYNAMIC_STUNE_BOOST
+	st->boost_default = boost;
+#endif /* CONFIG_DYNAMIC_STUNE_BOOST */
 	if (css == &root_schedtune.css) {
 		sysctl_sched_cfs_boost = boost;
 		perf_boost_idx  = threshold_idx;
@@ -738,6 +758,77 @@ schedtune_init_cgroups(void)
 	schedtune_initialized = true;
 }
 
+#ifdef CONFIG_DYNAMIC_STUNE_BOOST
+static struct schedtune *getSchedtune(char *st_name)
+{
+	int idx;
+
+	for (idx = 1; idx < BOOSTGROUPS_COUNT; ++idx) {
+		char name_buf[NAME_MAX + 1];
+		struct schedtune *st = allocated_group[idx];
+
+		if (!st) {
+			pr_warn("SCHEDTUNE: Could not find %s\n", st_name);
+			break;
+		}
+
+		cgroup_name(st->css.cgroup, name_buf, sizeof(name_buf));
+		if (strncmp(name_buf, st_name, strlen(st_name)) == 0)
+			return st;
+	}
+
+	return NULL;
+}
+
+static int dynamic_boost_write(struct schedtune *st, int boost)
+{
+	int ret;
+	/* Backup boost_default */
+	int boost_default_backup = st->boost_default;
+
+	ret = boost_write(&st->css, NULL, boost);
+
+	/* Restore boost_default */
+	st->boost_default = boost_default_backup;
+
+	return ret;
+}
+
+int do_stune_boost(char *st_name, int boost)
+{
+	int ret = 0;
+	struct schedtune *st = getSchedtune(st_name);
+
+	if (!st)
+		return -EINVAL;
+
+	mutex_lock(&stune_boost_mutex);
+
+	/* Boost if new value is greater than current */
+	if (boost > st->boost)
+		ret = dynamic_boost_write(st, boost);
+
+	mutex_unlock(&stune_boost_mutex);
+
+	return ret;
+}
+
+int reset_stune_boost(char *st_name)
+{
+	int ret = 0;
+	struct schedtune *st = getSchedtune(st_name);
+
+	if (!st)
+		return -EINVAL;
+
+	mutex_lock(&stune_boost_mutex);
+	ret = dynamic_boost_write(st, st->boost_default);
+	mutex_unlock(&stune_boost_mutex);
+
+	return ret;
+}
+#endif /* CONFIG_DYNAMIC_STUNE_BOOST */
+
 #else /* CONFIG_CGROUP_SCHEDTUNE */
 
 int