1 files changed, 91 insertions, 89 deletions

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 8d83a21c6477..c1fc9c62bb51 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)
 {