1 files changed, 91 insertions, 89 deletions

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 8d83a21..c1fc9c6 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -34,13 +34,9 @@
  */
 
 #define DEF_FREQUENCY_UP_THRESHOLD		(80)
-#define MIN_FREQUENCY_UP_THRESHOLD		(0)
+#define MIN_FREQUENCY_UP_THRESHOLD		(11)
 #define MAX_FREQUENCY_UP_THRESHOLD		(100)
 
-#define DEF_FREQUENCY_DOWN_THRESHOLD		(20)
-#define MIN_FREQUENCY_DOWN_THRESHOLD		(0)
-#define MAX_FREQUENCY_DOWN_THRESHOLD		(100)
-
 /* 
  * The polling frequency of this governor depends on the capability of 
  * the processor. Default polling frequency is 1000 times the transition
@@ -55,9 +51,9 @@ static unsigned int 				def_sampling_rate;
 #define MIN_SAMPLING_RATE			(def_sampling_rate / 2)
 #define MAX_SAMPLING_RATE			(500 * def_sampling_rate)
 #define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER	(1000)
-#define DEF_SAMPLING_DOWN_FACTOR		(10)
+#define DEF_SAMPLING_DOWN_FACTOR		(1)
+#define MAX_SAMPLING_DOWN_FACTOR		(10)
 #define TRANSITION_LATENCY_LIMIT		(10 * 1000)
-#define sampling_rate_in_HZ(x)			(((x * HZ) < (1000 * 1000))?1:((x * HZ) / (1000 * 1000)))
 
 static void do_dbs_timer(void *data);
 
@@ -78,15 +74,23 @@ struct dbs_tuners {
 	unsigned int 		sampling_rate;
 	unsigned int		sampling_down_factor;
 	unsigned int		up_threshold;
-	unsigned int		down_threshold;
+	unsigned int		ignore_nice;
 };
 
 static struct dbs_tuners dbs_tuners_ins = {
 	.up_threshold 		= DEF_FREQUENCY_UP_THRESHOLD,
-	.down_threshold 	= DEF_FREQUENCY_DOWN_THRESHOLD,
 	.sampling_down_factor 	= DEF_SAMPLING_DOWN_FACTOR,
 };
 
+static inline unsigned int get_cpu_idle_time(unsigned int cpu)
+{
+	return	kstat_cpu(cpu).cpustat.idle +
+		kstat_cpu(cpu).cpustat.iowait +
+		( !dbs_tuners_ins.ignore_nice ? 
+		  kstat_cpu(cpu).cpustat.nice :
+		  0);
+}
+
 /************************** sysfs interface ************************/
 static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
 {
@@ -115,7 +119,7 @@ static ssize_t show_##file_name						\
 show_one(sampling_rate, sampling_rate);
 show_one(sampling_down_factor, sampling_down_factor);
 show_one(up_threshold, up_threshold);
-show_one(down_threshold, down_threshold);
+show_one(ignore_nice, ignore_nice);
 
 static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused, 
 		const char *buf, size_t count)
@@ -126,6 +130,9 @@ static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
 	if (ret != 1 )
 		return -EINVAL;
 
+	if (input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
+		return -EINVAL;
+
 	down(&dbs_sem);
 	dbs_tuners_ins.sampling_down_factor = input;
 	up(&dbs_sem);
@@ -161,8 +168,7 @@ static ssize_t store_up_threshold(struct cpufreq_policy *unused,
 
 	down(&dbs_sem);
 	if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD || 
-			input < MIN_FREQUENCY_UP_THRESHOLD ||
-			input <= dbs_tuners_ins.down_threshold) {
+			input < MIN_FREQUENCY_UP_THRESHOLD) {
 		up(&dbs_sem);
 		return -EINVAL;
 	}
@@ -173,22 +179,35 @@ static ssize_t store_up_threshold(struct cpufreq_policy *unused,
 	return count;
 }
 
-static ssize_t store_down_threshold(struct cpufreq_policy *unused, 
+static ssize_t store_ignore_nice(struct cpufreq_policy *policy,
 		const char *buf, size_t count)
 {
 	unsigned int input;
 	int ret;
+
+	unsigned int j;
+	
 	ret = sscanf (buf, "%u", &input);
+	if ( ret != 1 )
+		return -EINVAL;
 
+	if ( input > 1 )
+		input = 1;
+	
 	down(&dbs_sem);
-	if (ret != 1 || input > MAX_FREQUENCY_DOWN_THRESHOLD || 
-			input < MIN_FREQUENCY_DOWN_THRESHOLD ||
-			input >= dbs_tuners_ins.up_threshold) {
+	if ( input == dbs_tuners_ins.ignore_nice ) { /* nothing to do */
 		up(&dbs_sem);
-		return -EINVAL;
+		return count;
 	}
+	dbs_tuners_ins.ignore_nice = input;
 
-	dbs_tuners_ins.down_threshold = input;
+	/* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */
+	for_each_online_cpu(j) {
+		struct cpu_dbs_info_s *j_dbs_info;
+		j_dbs_info = &per_cpu(cpu_dbs_info, j);
+		j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
+		j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up;
+	}
 	up(&dbs_sem);
 
 	return count;
@@ -201,7 +220,7 @@ __ATTR(_name, 0644, show_##_name, store_##_name)
 define_one_rw(sampling_rate);
 define_one_rw(sampling_down_factor);
 define_one_rw(up_threshold);
-define_one_rw(down_threshold);
+define_one_rw(ignore_nice);
 
 static struct attribute * dbs_attributes[] = {
 	&sampling_rate_max.attr,
@@ -209,7 +228,7 @@ static struct attribute * dbs_attributes[] = {
 	&sampling_rate.attr,
 	&sampling_down_factor.attr,
 	&up_threshold.attr,
-	&down_threshold.attr,
+	&ignore_nice.attr,
 	NULL
 };
 
@@ -222,9 +241,8 @@ static struct attribute_group dbs_attr_group = {
 
 static void dbs_check_cpu(int cpu)
 {
-	unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
-	unsigned int total_idle_ticks;
-	unsigned int freq_down_step;
+	unsigned int idle_ticks, up_idle_ticks, total_ticks;
+	unsigned int freq_next;
 	unsigned int freq_down_sampling_rate;
 	static int down_skip[NR_CPUS];
 	struct cpu_dbs_info_s *this_dbs_info;
@@ -238,38 +256,25 @@ static void dbs_check_cpu(int cpu)
 
 	policy = this_dbs_info->cur_policy;
 	/* 
-	 * The default safe range is 20% to 80% 
-	 * Every sampling_rate, we check
-	 * 	- If current idle time is less than 20%, then we try to 
-	 * 	  increase frequency
-	 * Every sampling_rate*sampling_down_factor, we check
-	 * 	- If current idle time is more than 80%, then we try to
-	 * 	  decrease frequency
+	 * Every sampling_rate, we check, if current idle time is less
+	 * than 20% (default), then we try to increase frequency
+	 * Every sampling_rate*sampling_down_factor, we look for a the lowest
+	 * frequency which can sustain the load while keeping idle time over
+	 * 30%. If such a frequency exist, we try to decrease to this frequency.
 	 *
 	 * Any frequency increase takes it to the maximum frequency. 
 	 * Frequency reduction happens at minimum steps of 
-	 * 5% of max_frequency 
+	 * 5% (default) of current frequency 
 	 */
 
 	/* Check for frequency increase */
-	total_idle_ticks = kstat_cpu(cpu).cpustat.idle +
-		kstat_cpu(cpu).cpustat.iowait;
-	idle_ticks = total_idle_ticks -
-		this_dbs_info->prev_cpu_idle_up;
-	this_dbs_info->prev_cpu_idle_up = total_idle_ticks;
-	
-
+	idle_ticks = UINT_MAX;
 	for_each_cpu_mask(j, policy->cpus) {
-		unsigned int tmp_idle_ticks;
+		unsigned int tmp_idle_ticks, total_idle_ticks;
 		struct cpu_dbs_info_s *j_dbs_info;
 
-		if (j == cpu)
-			continue;
-
 		j_dbs_info = &per_cpu(cpu_dbs_info, j);
-		/* Check for frequency increase */
-		total_idle_ticks = kstat_cpu(j).cpustat.idle +
-			kstat_cpu(j).cpustat.iowait;
+		total_idle_ticks = get_cpu_idle_time(j);
 		tmp_idle_ticks = total_idle_ticks -
 			j_dbs_info->prev_cpu_idle_up;
 		j_dbs_info->prev_cpu_idle_up = total_idle_ticks;
@@ -281,13 +286,23 @@ static void dbs_check_cpu(int cpu)
 	/* Scale idle ticks by 100 and compare with up and down ticks */
 	idle_ticks *= 100;
 	up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
-			sampling_rate_in_HZ(dbs_tuners_ins.sampling_rate);
+			usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
 
 	if (idle_ticks < up_idle_ticks) {
+		down_skip[cpu] = 0;
+		for_each_cpu_mask(j, policy->cpus) {
+			struct cpu_dbs_info_s *j_dbs_info;
+
+			j_dbs_info = &per_cpu(cpu_dbs_info, j);
+			j_dbs_info->prev_cpu_idle_down = 
+					j_dbs_info->prev_cpu_idle_up;
+		}
+		/* if we are already at full speed then break out early */
+		if (policy->cur == policy->max)
+			return;
+		
 		__cpufreq_driver_target(policy, policy->max, 
 			CPUFREQ_RELATION_H);
-		down_skip[cpu] = 0;
-		this_dbs_info->prev_cpu_idle_down = total_idle_ticks;
 		return;
 	}
 
@@ -296,23 +311,14 @@ static void dbs_check_cpu(int cpu)
 	if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor)
 		return;
 
-	total_idle_ticks = kstat_cpu(cpu).cpustat.idle +
-		kstat_cpu(cpu).cpustat.iowait;
-	idle_ticks = total_idle_ticks -
-		this_dbs_info->prev_cpu_idle_down;
-	this_dbs_info->prev_cpu_idle_down = total_idle_ticks;
-
+	idle_ticks = UINT_MAX;
 	for_each_cpu_mask(j, policy->cpus) {
-		unsigned int tmp_idle_ticks;
+		unsigned int tmp_idle_ticks, total_idle_ticks;
 		struct cpu_dbs_info_s *j_dbs_info;
 
-		if (j == cpu)
-			continue;
-
 		j_dbs_info = &per_cpu(cpu_dbs_info, j);
-		/* Check for frequency increase */
-		total_idle_ticks = kstat_cpu(j).cpustat.idle +
-			kstat_cpu(j).cpustat.iowait;
+		/* Check for frequency decrease */
+		total_idle_ticks = j_dbs_info->prev_cpu_idle_up;
 		tmp_idle_ticks = total_idle_ticks -
 			j_dbs_info->prev_cpu_idle_down;
 		j_dbs_info->prev_cpu_idle_down = total_idle_ticks;
@@ -321,38 +327,37 @@ static void dbs_check_cpu(int cpu)
 			idle_ticks = tmp_idle_ticks;
 	}
 
-	/* Scale idle ticks by 100 and compare with up and down ticks */
-	idle_ticks *= 100;
 	down_skip[cpu] = 0;
+	/* if we cannot reduce the frequency anymore, break out early */
+	if (policy->cur == policy->min)
+		return;
 
+	/* Compute how many ticks there are between two measurements */
 	freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
 		dbs_tuners_ins.sampling_down_factor;
-	down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) *
-			sampling_rate_in_HZ(freq_down_sampling_rate);
+	total_ticks = usecs_to_jiffies(freq_down_sampling_rate);
 
-	if (idle_ticks > down_idle_ticks ) {
-		freq_down_step = (5 * policy->max) / 100;
-
-		/* max freq cannot be less than 100. But who knows.... */
-		if (unlikely(freq_down_step == 0))
-			freq_down_step = 5;
+	/*
+	 * The optimal frequency is the frequency that is the lowest that
+	 * can support the current CPU usage without triggering the up
+	 * policy. To be safe, we focus 10 points under the threshold.
+	 */
+	freq_next = ((total_ticks - idle_ticks) * 100) / total_ticks;
+	freq_next = (freq_next * policy->cur) / 
+			(dbs_tuners_ins.up_threshold - 10);
 
-		__cpufreq_driver_target(policy,
-			policy->cur - freq_down_step, 
-			CPUFREQ_RELATION_H);
-		return;
-	}
+	if (freq_next <= ((policy->cur * 95) / 100))
+		__cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_L);
 }
 
 static void do_dbs_timer(void *data)
 { 
 	int i;
 	down(&dbs_sem);
-	for (i = 0; i < NR_CPUS; i++)
-		if (cpu_online(i))
-			dbs_check_cpu(i);
+	for_each_online_cpu(i)
+		dbs_check_cpu(i);
 	schedule_delayed_work(&dbs_work, 
-			sampling_rate_in_HZ(dbs_tuners_ins.sampling_rate));
+			usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
 	up(&dbs_sem);
 } 
 
@@ -360,7 +365,7 @@ static inline void dbs_timer_init(void)
 {
 	INIT_WORK(&dbs_work, do_dbs_timer, NULL);
 	schedule_delayed_work(&dbs_work,
-			sampling_rate_in_HZ(dbs_tuners_ins.sampling_rate));
+			usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
 	return;
 }
 
@@ -397,12 +402,9 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 			j_dbs_info = &per_cpu(cpu_dbs_info, j);
 			j_dbs_info->cur_policy = policy;
 		
-			j_dbs_info->prev_cpu_idle_up = 
-				kstat_cpu(j).cpustat.idle +
-				kstat_cpu(j).cpustat.iowait;
-			j_dbs_info->prev_cpu_idle_down = 
-				kstat_cpu(j).cpustat.idle +
-				kstat_cpu(j).cpustat.iowait;
+			j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
+			j_dbs_info->prev_cpu_idle_down
+				= j_dbs_info->prev_cpu_idle_up;
 		}
 		this_dbs_info->enable = 1;
 		sysfs_create_group(&policy->kobj, &dbs_attr_group);
@@ -422,6 +424,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 			def_sampling_rate = (latency / 1000) *
 					DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
 			dbs_tuners_ins.sampling_rate = def_sampling_rate;
+			dbs_tuners_ins.ignore_nice = 0;
 
 			dbs_timer_init();
 		}
@@ -461,12 +464,11 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 	return 0;
 }
 
-struct cpufreq_governor cpufreq_gov_dbs = {
+static struct cpufreq_governor cpufreq_gov_dbs = {
 	.name		= "ondemand",
 	.governor	= cpufreq_governor_dbs,
 	.owner		= THIS_MODULE,
 };
-EXPORT_SYMBOL(cpufreq_gov_dbs);
 
 static int __init cpufreq_gov_dbs_init(void)
 {