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path: root/drivers/cpufreq/cpufreq_ondemand.c
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Diffstat (limited to 'drivers/cpufreq/cpufreq_ondemand.c')
-rw-r--r--drivers/cpufreq/cpufreq_ondemand.c75
1 files changed, 73 insertions, 2 deletions
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index bd444dc93cf2..8e9dbdc6c700 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -73,6 +73,7 @@ enum {DBS_NORMAL_SAMPLE, DBS_SUB_SAMPLE};
struct cpu_dbs_info_s {
cputime64_t prev_cpu_idle;
+ cputime64_t prev_cpu_iowait;
cputime64_t prev_cpu_wall;
cputime64_t prev_cpu_nice;
struct cpufreq_policy *cur_policy;
@@ -108,6 +109,7 @@ static struct dbs_tuners {
unsigned int down_differential;
unsigned int ignore_nice;
unsigned int powersave_bias;
+ unsigned int io_is_busy;
} dbs_tuners_ins = {
.up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
.down_differential = DEF_FREQUENCY_DOWN_DIFFERENTIAL,
@@ -148,6 +150,16 @@ static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
return idle_time;
}
+static inline cputime64_t get_cpu_iowait_time(unsigned int cpu, cputime64_t *wall)
+{
+ u64 iowait_time = get_cpu_iowait_time_us(cpu, wall);
+
+ if (iowait_time == -1ULL)
+ return 0;
+
+ return iowait_time;
+}
+
/*
* Find right freq to be set now with powersave_bias on.
* Returns the freq_hi to be used right now and will set freq_hi_jiffies,
@@ -249,6 +261,7 @@ static ssize_t show_##file_name \
return sprintf(buf, "%u\n", dbs_tuners_ins.object); \
}
show_one(sampling_rate, sampling_rate);
+show_one(io_is_busy, io_is_busy);
show_one(up_threshold, up_threshold);
show_one(ignore_nice_load, ignore_nice);
show_one(powersave_bias, powersave_bias);
@@ -299,6 +312,23 @@ static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
return count;
}
+static ssize_t store_io_is_busy(struct kobject *a, struct attribute *b,
+ const char *buf, size_t count)
+{
+ unsigned int input;
+ int ret;
+
+ ret = sscanf(buf, "%u", &input);
+ if (ret != 1)
+ return -EINVAL;
+
+ mutex_lock(&dbs_mutex);
+ dbs_tuners_ins.io_is_busy = !!input;
+ mutex_unlock(&dbs_mutex);
+
+ return count;
+}
+
static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
const char *buf, size_t count)
{
@@ -381,6 +411,7 @@ static struct global_attr _name = \
__ATTR(_name, 0644, show_##_name, store_##_name)
define_one_rw(sampling_rate);
+define_one_rw(io_is_busy);
define_one_rw(up_threshold);
define_one_rw(ignore_nice_load);
define_one_rw(powersave_bias);
@@ -392,6 +423,7 @@ static struct attribute *dbs_attributes[] = {
&up_threshold.attr,
&ignore_nice_load.attr,
&powersave_bias.attr,
+ &io_is_busy.attr,
NULL
};
@@ -470,14 +502,15 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
for_each_cpu(j, policy->cpus) {
struct cpu_dbs_info_s *j_dbs_info;
- cputime64_t cur_wall_time, cur_idle_time;
- unsigned int idle_time, wall_time;
+ cputime64_t cur_wall_time, cur_idle_time, cur_iowait_time;
+ unsigned int idle_time, wall_time, iowait_time;
unsigned int load, load_freq;
int freq_avg;
j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
+ cur_iowait_time = get_cpu_iowait_time(j, &cur_wall_time);
wall_time = (unsigned int) cputime64_sub(cur_wall_time,
j_dbs_info->prev_cpu_wall);
@@ -487,6 +520,10 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
j_dbs_info->prev_cpu_idle);
j_dbs_info->prev_cpu_idle = cur_idle_time;
+ iowait_time = (unsigned int) cputime64_sub(cur_iowait_time,
+ j_dbs_info->prev_cpu_iowait);
+ j_dbs_info->prev_cpu_iowait = cur_iowait_time;
+
if (dbs_tuners_ins.ignore_nice) {
cputime64_t cur_nice;
unsigned long cur_nice_jiffies;
@@ -504,6 +541,16 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
idle_time += jiffies_to_usecs(cur_nice_jiffies);
}
+ /*
+ * For the purpose of ondemand, waiting for disk IO is an
+ * indication that you're performance critical, and not that
+ * the system is actually idle. So subtract the iowait time
+ * from the cpu idle time.
+ */
+
+ if (dbs_tuners_ins.io_is_busy && idle_time >= iowait_time)
+ idle_time -= iowait_time;
+
if (unlikely(!wall_time || wall_time < idle_time))
continue;
@@ -617,6 +664,29 @@ static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
cancel_delayed_work_sync(&dbs_info->work);
}
+/*
+ * Not all CPUs want IO time to be accounted as busy; this dependson how
+ * efficient idling at a higher frequency/voltage is.
+ * Pavel Machek says this is not so for various generations of AMD and old
+ * Intel systems.
+ * Mike Chan (androidlcom) calis this is also not true for ARM.
+ * Because of this, whitelist specific known (series) of CPUs by default, and
+ * leave all others up to the user.
+ */
+static int should_io_be_busy(void)
+{
+#if defined(CONFIG_X86)
+ /*
+ * For Intel, Core 2 (model 15) andl later have an efficient idle.
+ */
+ if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
+ boot_cpu_data.x86 == 6 &&
+ boot_cpu_data.x86_model >= 15)
+ return 1;
+#endif
+ return 0;
+}
+
static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
unsigned int event)
{
@@ -679,6 +749,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
dbs_tuners_ins.sampling_rate =
max(min_sampling_rate,
latency * LATENCY_MULTIPLIER);
+ dbs_tuners_ins.io_is_busy = should_io_be_busy();
}
mutex_unlock(&dbs_mutex);