sched/walt: Improve the scheduler

This change is for general scheduler improvement.

Change-Id: I8459bcf7b412a5f301566054c28c910567548485
Signed-off-by: Sai Harshini Nimmala <snimmala@codeaurora.org>

include/linux/sched/sysctl.h

@@ -53,6 +53,7 @@ extern unsigned int sysctl_sched_coloc_busy_hyst_enable_cpus;
 extern unsigned int sysctl_sched_coloc_busy_hyst;
 extern unsigned int sysctl_sched_coloc_busy_hyst_max_ms;
 extern unsigned int sysctl_sched_window_stats_policy;
+extern unsigned int sysctl_sched_ravg_window_nr_ticks;
 
 extern int
 walt_proc_group_thresholds_handler(struct ctl_table *table, int write,
@@ -63,6 +64,11 @@ walt_proc_user_hint_handler(struct ctl_table *table, int write,
 			 void __user *buffer, size_t *lenp,
 			 loff_t *ppos);
 
+extern int
+sched_ravg_window_handler(struct ctl_table *table, int write,
+			 void __user *buffer, size_t *lenp,
+			 loff_t *ppos);
+
 #endif
 
 #if defined(CONFIG_PREEMPT_TRACER) || defined(CONFIG_DEBUG_PREEMPT)

include/linux/sysctl.h

@@ -67,6 +67,10 @@ extern int proc_douintvec_capacity(struct ctl_table *table, int write,
 				   void __user *buffer, size_t *lenp,
 				   loff_t *ppos);
 
+extern int proc_douintvec_ravg_window(struct ctl_table *table, int write,
+				      void __user *buffer, size_t *lenp,
+				      loff_t *ppos);
+
 /*
  * Register a set of sysctl names by calling register_sysctl_table
  * with an initialised array of struct ctl_table's.  An entry with 

kernel/sched/walt.c

@@ -108,6 +108,8 @@ static void release_rq_locks_irqrestore(const cpumask_t *cpus,
 /* Max window size (in ns) = 1s */
 #define MAX_SCHED_RAVG_WINDOW 1000000000
 
+#define NR_WINDOWS_PER_SEC (NSEC_PER_SEC / MIN_SCHED_RAVG_WINDOW)
+
 __read_mostly unsigned int sysctl_sched_cpu_high_irqload = (10 * NSEC_PER_MSEC);
 
 unsigned int sysctl_sched_walt_rotate_big_tasks;
@@ -121,6 +123,9 @@ static __read_mostly unsigned int sched_io_is_busy = 1;
 __read_mostly unsigned int sysctl_sched_window_stats_policy =
 	WINDOW_STATS_MAX_RECENT_AVG;
 
+__read_mostly unsigned int sysctl_sched_ravg_window_nr_ticks =
+	(HZ / NR_WINDOWS_PER_SEC);
+
 /* Window size (in ns) */
 __read_mostly unsigned int sched_ravg_window = MIN_SCHED_RAVG_WINDOW;
 __read_mostly unsigned int new_sched_ravg_window = MIN_SCHED_RAVG_WINDOW;
@@ -3552,3 +3557,32 @@ int walt_proc_user_hint_handler(struct ctl_table *table,
 	mutex_unlock(&mutex);
 	return ret;
 }
+
+static inline void sched_window_nr_ticks_change(int new_nr_ticks)
+{
+	new_sched_ravg_window = new_nr_ticks * (NSEC_PER_SEC / HZ);
+}
+
+int sched_ravg_window_handler(struct ctl_table *table,
+				int write, void __user *buffer, size_t *lenp,
+				loff_t *ppos)
+{
+	int ret;
+	static DEFINE_MUTEX(mutex);
+	unsigned int prev_value;
+
+	mutex_lock(&mutex);
+
+	prev_value = sysctl_sched_ravg_window_nr_ticks;
+	ret = proc_douintvec_ravg_window(table, write, buffer, lenp, ppos);
+	if (ret || !write ||
+			(prev_value == sysctl_sched_ravg_window_nr_ticks) ||
+			(sysctl_sched_ravg_window_nr_ticks == 0))
+		goto unlock;
+
+	sched_window_nr_ticks_change(sysctl_sched_ravg_window_nr_ticks);
+
+unlock:
+	mutex_unlock(&mutex);
+	return ret;
+}

kernel/sysctl.c

@@ -511,6 +511,13 @@ static struct ctl_table kern_table[] = {
 		.extra1		= &zero,
 		.extra2		= &one_hundred_thousand,
 	},
+	{
+		.procname	= "sched_ravg_window_nr_ticks",
+		.data		= &sysctl_sched_ravg_window_nr_ticks,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= sched_ravg_window_handler,
+	},
 #endif
 #ifdef CONFIG_SMP
 	{
@@ -3544,6 +3551,29 @@ int proc_douintvec_capacity(struct ctl_table *table, int write,
 				do_proc_douintvec_capacity_conv, NULL);
 }
 
+static int do_proc_douintvec_rwin(bool *negp, unsigned long *lvalp,
+				  int *valp, int write, void *data)
+{
+	if (write) {
+		if (*lvalp == 0 || *lvalp == 2 || *lvalp == 5)
+			*valp = *lvalp;
+		else
+			return -EINVAL;
+	} else {
+		*negp = false;
+		*lvalp = *valp;
+	}
+
+	return 0;
+}
+
+int proc_douintvec_ravg_window(struct ctl_table *table, int write,
+			       void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	return do_proc_dointvec(table, write, buffer, lenp, ppos,
+				do_proc_douintvec_rwin, NULL);
+}
+
 #else /* CONFIG_PROC_SYSCTL */
 
 int proc_dostring(struct ctl_table *table, int write,
@@ -3613,6 +3643,12 @@ int proc_douintvec_capacity(struct ctl_table *table, int write,
 	return -ENOSYS;
 }
 
+int proc_douintvec_ravg_window(struct ctl_table *table, int write,
+			       void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	return -ENOSYS;
+}
+
 #endif /* CONFIG_PROC_SYSCTL */
 
 /*