1 files changed, 41 insertions, 1 deletions

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 7b5093664e49..c631f27a3dcc 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -30,6 +30,8 @@
 
 #define DEF_FREQUENCY_DOWN_DIFFERENTIAL         (10)
 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
+#define DEF_SAMPLING_DOWN_FACTOR                (1)
+#define MAX_SAMPLING_DOWN_FACTOR                (100000)
 #define MICRO_FREQUENCY_DOWN_DIFFERENTIAL       (3)
 #define MICRO_FREQUENCY_UP_THRESHOLD            (95)
 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE         (10000)
@@ -82,6 +84,7 @@ struct cpu_dbs_info_s {
         unsigned int freq_lo;
         unsigned int freq_lo_jiffies;
         unsigned int freq_hi_jiffies;
+        unsigned int rate_mult;
         int cpu;
         unsigned int sample_type:1;
         /*
@@ -108,10 +111,12 @@ static struct dbs_tuners {
         unsigned int up_threshold;
         unsigned int down_differential;
         unsigned int ignore_nice;
+        unsigned int sampling_down_factor;
         unsigned int powersave_bias;
         unsigned int io_is_busy;
 } dbs_tuners_ins = {
         .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
+        .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
         .down_differential = DEF_FREQUENCY_DOWN_DIFFERENTIAL,
         .ignore_nice = 0,
         .powersave_bias = 0,
@@ -259,6 +264,7 @@ static ssize_t show_##file_name						\
 show_one(sampling_rate, sampling_rate);
 show_one(io_is_busy, io_is_busy);
 show_one(up_threshold, up_threshold);
+show_one(sampling_down_factor, sampling_down_factor);
 show_one(ignore_nice_load, ignore_nice);
 show_one(powersave_bias, powersave_bias);
 
@@ -340,6 +346,29 @@ static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
         return count;
 }
 
+static ssize_t store_sampling_down_factor(struct kobject *a,
+                        struct attribute *b, const char *buf, size_t count)
+{
+        unsigned int input, j;
+        int ret;
+        ret = sscanf(buf, "%u", &input);
+
+        if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
+                return -EINVAL;
+        mutex_lock(&dbs_mutex);
+        dbs_tuners_ins.sampling_down_factor = input;
+
+        /* Reset down sampling multiplier in case it was active */
+        for_each_online_cpu(j) {
+                struct cpu_dbs_info_s *dbs_info;
+                dbs_info = &per_cpu(od_cpu_dbs_info, j);
+                dbs_info->rate_mult = 1;
+        }
+        mutex_unlock(&dbs_mutex);
+
+        return count;
+}
+
 static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
                                       const char *buf, size_t count)
 {
@@ -401,6 +430,7 @@ static ssize_t store_powersave_bias(struct kobject *a, struct attribute *b,
 define_one_global_rw(sampling_rate);
 define_one_global_rw(io_is_busy);
 define_one_global_rw(up_threshold);
+define_one_global_rw(sampling_down_factor);
 define_one_global_rw(ignore_nice_load);
 define_one_global_rw(powersave_bias);
 
@@ -409,6 +439,7 @@ static struct attribute *dbs_attributes[] = {
         &sampling_rate_min.attr,
         &sampling_rate.attr,
         &up_threshold.attr,
+        &sampling_down_factor.attr,
         &ignore_nice_load.attr,
         &powersave_bias.attr,
         &io_is_busy.attr,
@@ -562,6 +593,10 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 
         /* Check for frequency increase */
         if (max_load_freq > dbs_tuners_ins.up_threshold * policy->cur) {
+                /* If switching to max speed, apply sampling_down_factor */
+                if (policy->cur < policy->max)
+                        this_dbs_info->rate_mult =
+                                dbs_tuners_ins.sampling_down_factor;
                 dbs_freq_increase(policy, policy->max);
                 return;
         }
@@ -584,6 +619,9 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
                                 (dbs_tuners_ins.up_threshold -
                                  dbs_tuners_ins.down_differential);
 
+                /* No longer fully busy, reset rate_mult */
+                this_dbs_info->rate_mult = 1;
+
                 if (freq_next < policy->min)
                         freq_next = policy->min;
 
@@ -607,7 +645,8 @@ static void do_dbs_timer(struct work_struct *work)
         int sample_type = dbs_info->sample_type;
 
         /* We want all CPUs to do sampling nearly on same jiffy */
-        int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
+        int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate
+                * dbs_info->rate_mult);
 
         if (num_online_cpus() > 1)
                 delay -= jiffies % delay;
@@ -711,6 +750,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                         }
                 }
                 this_dbs_info->cpu = cpu;
+                this_dbs_info->rate_mult = 1;
                 ondemand_powersave_bias_init_cpu(cpu);
                 /*
                  * Start the timerschedule work, when this governor