sched: window-stats: Allow acct_wait_time to be tuned

Add sysctl interface to tune sched_acct_wait_time variable at runtime

Change-Id: I38339cdb388a507019e429709a7c28e80b5b3585
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>

include/linux/sched/sysctl.h

@@ -42,6 +42,7 @@ extern unsigned int sysctl_sched_child_runs_first;
 extern unsigned int sysctl_sched_wake_to_idle;
 extern unsigned int sysctl_sched_wakeup_load_threshold;
 extern unsigned int sysctl_sched_window_stats_policy;
+extern unsigned int sysctl_sched_account_wait_time;
 
 #if defined(CONFIG_SCHED_FREQ_INPUT) || defined(CONFIG_SCHED_HMP)
 extern unsigned int sysctl_sched_init_task_load_pct;
@@ -103,6 +104,9 @@ extern int sched_hmp_proc_update_handler(struct ctl_table *table,
 extern int sched_boost_handler(struct ctl_table *table, int write,
 			void __user *buffer, size_t *lenp, loff_t *ppos);
 
+extern int sched_acct_wait_time_update_handler(struct ctl_table *table,
+		 int write, void __user *buffer, size_t *lenp, loff_t *ppos);
+
 extern int sched_window_stats_policy_update_handler(struct ctl_table *table,
 		 int write, void __user *buffer, size_t *lenp, loff_t *ppos);
 

kernel/sched/core.c

@@ -1195,7 +1195,14 @@ unsigned int min_possible_efficiency = 1024;
 
 __read_mostly int sysctl_sched_freq_inc_notify_slack_pct;
 __read_mostly int sysctl_sched_freq_dec_notify_slack_pct = 25;
+
 static __read_mostly unsigned int sched_account_wait_time = 1;
+/*
+ * Copy of sched_account_wait_time, used to change it atomically.
+ * Initialize both variables to same value!!
+ */
+__read_mostly unsigned int sysctl_sched_account_wait_time = 1;
+
 static __read_mostly unsigned int sched_io_is_busy;
 
 /*
@@ -1682,7 +1689,7 @@ unsigned long sched_get_busy(int cpu)
 
 /* Called with IRQs disabled */
 void reset_all_window_stats(u64 window_start, unsigned int window_size,
-				 int policy)
+				 int policy, int acct_wait_time)
 {
 	int cpu;
 	u64 wallclock;
@@ -1728,6 +1735,9 @@ void reset_all_window_stats(u64 window_start, unsigned int window_size,
 	if (policy >= 0)
 		sched_window_stats_policy = policy;
 
+	if (acct_wait_time >= 0)
+		sched_account_wait_time = acct_wait_time;
+
 	for_each_online_cpu(cpu) {
 		struct rq *rq = cpu_rq(cpu);
 		raw_spin_unlock(&rq->lock);
@@ -1765,7 +1775,7 @@ int sched_set_window(u64 window_start, unsigned int window_size)
 
 	BUG_ON(sched_clock() < ws);
 
-	reset_all_window_stats(ws, window_size, -1);
+	reset_all_window_stats(ws, window_size, -1, -1);
 
 	local_irq_restore(flags);
 

kernel/sched/fair.c

@@ -3202,6 +3202,38 @@ void post_big_small_task_count_change(void)
 
 static DEFINE_MUTEX(policy_mutex);
 
+int sched_acct_wait_time_update_handler(struct ctl_table *table, int write,
+		void __user *buffer, size_t *lenp,
+		loff_t *ppos)
+{
+	int ret;
+	unsigned int *data = (unsigned int *)table->data;
+	unsigned int old_val;
+	unsigned long flags;
+
+	if (!sched_enable_hmp)
+		return -EINVAL;
+
+	mutex_lock(&policy_mutex);
+
+	old_val = *data;
+
+	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+	if (ret || !write || (write && old_val == *data))
+		goto done;
+
+	local_irq_save(flags);
+
+	reset_all_window_stats(0, 0, -1, sysctl_sched_account_wait_time);
+
+	local_irq_restore(flags);
+
+done:
+	mutex_unlock(&policy_mutex);
+
+	return ret;
+}
+
 int sched_window_stats_policy_update_handler(struct ctl_table *table, int write,
 		void __user *buffer, size_t *lenp,
 		loff_t *ppos)
@@ -3224,7 +3256,7 @@ int sched_window_stats_policy_update_handler(struct ctl_table *table, int write,
 
 	local_irq_save(flags);
 
-	reset_all_window_stats(0, 0, sysctl_sched_window_stats_policy);
+	reset_all_window_stats(0, 0, sysctl_sched_window_stats_policy, -1);
 
 	local_irq_restore(flags);
 

kernel/sched/sched.h

@@ -1061,7 +1061,7 @@ extern void dec_nr_big_small_task(struct rq *rq, struct task_struct *p);
 extern void set_hmp_defaults(void);
 extern unsigned int power_cost_at_freq(int cpu, unsigned int freq);
 extern void reset_all_window_stats(u64 window_start, unsigned int window_size,
-				 int policy);
+				 int policy, int acct_wait_time);
 extern void boost_kick(int cpu);
 
 #else /* CONFIG_SCHED_HMP */

kernel/sysctl.c

@@ -309,6 +309,13 @@ static struct ctl_table kern_table[] = {
 	},
 #endif
 #if defined(CONFIG_SCHED_FREQ_INPUT) || defined(CONFIG_SCHED_HMP)
+	{
+		.procname       = "sched_account_wait_time",
+		.data           = &sysctl_sched_account_wait_time,
+		.maxlen         = sizeof(unsigned int),
+		.mode           = 0644,
+		.proc_handler   = sched_acct_wait_time_update_handler,
+	},
 	{
 		.procname       = "sched_window_stats_policy",
 		.data           = &sysctl_sched_window_stats_policy,