[CPUFREQ] conservative: fixup governor to function more like ondemand logic

As conservative is based off ondemand the codebases occasionally need to be
resync'd.  This patch, although ugly, does this.

Signed-off-by: Alexander Clouter <alex@digriz.org.uk>
Signed-off-by: Dave Jones <davej@redhat.com>

1 files changed, 188 insertions, 140 deletions

diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
index a16a5b8c1dc5..c9bd0c55ad1e 100644
--- a/drivers/cpufreq/cpufreq_conservative.c
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -13,22 +13,17 @@
 
 #include <linux/kernel.h>
 #include <linux/module.h>
-#include <linux/smp.h>
 #include <linux/init.h>
-#include <linux/interrupt.h>
-#include <linux/ctype.h>
 #include <linux/cpufreq.h>
-#include <linux/sysctl.h>
-#include <linux/types.h>
-#include <linux/fs.h>
-#include <linux/sysfs.h>
 #include <linux/cpu.h>
-#include <linux/kmod.h>
-#include <linux/workqueue.h>
 #include <linux/jiffies.h>
 #include <linux/kernel_stat.h>
-#include <linux/percpu.h>
 #include <linux/mutex.h>
+#include <linux/hrtimer.h>
+#include <linux/tick.h>
+#include <linux/ktime.h>
+#include <linux/sched.h>
+
 /*
  * dbs is used in this file as a shortform for demandbased switching
  * It helps to keep variable names smaller, simpler
@@ -43,14 +38,14 @@
  * latency of the processor. The governor will work on any processor with
  * transition latency <= 10mS, using appropriate sampling
  * rate.
- * For CPUs with transition latency > 10mS (mostly drivers
- * with CPUFREQ_ETERNAL), this governor will not work.
+ * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
+ * this governor will not work.
  * All times here are in uS.
  */
 static unsigned int def_sampling_rate;
 #define MIN_SAMPLING_RATE_RATIO                 (2)
 /* for correct statistics, we need at least 10 ticks between each measure */
-#define MIN_STAT_SAMPLING_RATE                  \
+#define MIN_STAT_SAMPLING_RATE                  \
                         (MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10))
 #define MIN_SAMPLING_RATE                       \
                         (def_sampling_rate / MIN_SAMPLING_RATE_RATIO)
@@ -75,12 +70,15 @@ static unsigned int minimum_sampling_rate(void)
 static void do_dbs_timer(struct work_struct *work);
 
 struct cpu_dbs_info_s {
+        cputime64_t prev_cpu_idle;
+        cputime64_t prev_cpu_wall;
+        cputime64_t prev_cpu_nice;
         struct cpufreq_policy *cur_policy;
-        unsigned int prev_cpu_idle_up;
-        unsigned int prev_cpu_idle_down;
-        unsigned int enable;
+        struct delayed_work work;
         unsigned int down_skip;
         unsigned int requested_freq;
+        int cpu;
+        unsigned int enable:1;
 };
 static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
 
@@ -95,18 +93,17 @@ static unsigned int dbs_enable;	/* number of CPUs using this policy */
  * is recursive for the same process. -Venki
  */
 static DEFINE_MUTEX(dbs_mutex);
-static DECLARE_DELAYED_WORK(dbs_work, do_dbs_timer);
 
-struct dbs_tuners {
+static struct workqueue_struct  *kconservative_wq;
+
+static struct dbs_tuners {
         unsigned int sampling_rate;
         unsigned int sampling_down_factor;
         unsigned int up_threshold;
         unsigned int down_threshold;
         unsigned int ignore_nice;
         unsigned int freq_step;
-};
-
-static struct dbs_tuners dbs_tuners_ins = {
+} dbs_tuners_ins = {
         .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
         .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
         .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
@@ -114,18 +111,37 @@ static struct dbs_tuners dbs_tuners_ins = {
         .freq_step = 5,
 };
 
-static inline unsigned int get_cpu_idle_time(unsigned int cpu)
+static inline cputime64_t get_cpu_idle_time_jiffy(unsigned int cpu,
+                                                        cputime64_t *wall)
 {
-        unsigned int add_nice = 0, ret;
+        cputime64_t idle_time;
+        cputime64_t cur_wall_time;
+        cputime64_t busy_time;
+
+        cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
+        busy_time = cputime64_add(kstat_cpu(cpu).cpustat.user,
+                        kstat_cpu(cpu).cpustat.system);
 
-        if (dbs_tuners_ins.ignore_nice)
-                add_nice = kstat_cpu(cpu).cpustat.nice;
+        busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.irq);
+        busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.softirq);
+        busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.steal);
+        busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.nice);
 
-        ret = kstat_cpu(cpu).cpustat.idle +
-                kstat_cpu(cpu).cpustat.iowait +
-                add_nice;
+        idle_time = cputime64_sub(cur_wall_time, busy_time);
+        if (wall)
+                *wall = cur_wall_time;
 
-        return ret;
+        return idle_time;
+}
+
+static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
+{
+        u64 idle_time = get_cpu_idle_time_us(cpu, wall);
+
+        if (idle_time == -1ULL)
+                return get_cpu_idle_time_jiffy(cpu, wall);
+
+        return idle_time;
 }
 
 /* keep track of frequency transitions */
@@ -186,8 +202,8 @@ static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
         return sprintf(buf, "%u\n", MIN_SAMPLING_RATE);
 }
 
-#define define_one_ro(_name)                            \
-static struct freq_attr _name =                         \
+#define define_one_ro(_name)            \
+static struct freq_attr _name =         \
 __ATTR(_name, 0444, show_##_name, NULL)
 
 define_one_ro(sampling_rate_max);
@@ -213,6 +229,7 @@ static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
         unsigned int input;
         int ret;
         ret = sscanf(buf, "%u", &input);
+
         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
                 return -EINVAL;
 
@@ -230,11 +247,10 @@ static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
         int ret;
         ret = sscanf(buf, "%u", &input);
 
-        mutex_lock(&dbs_mutex);
-        if (ret != 1) {
-                mutex_unlock(&dbs_mutex);
+        if (ret != 1)
                 return -EINVAL;
-        }
+
+        mutex_lock(&dbs_mutex);
         dbs_tuners_ins.sampling_rate = max(input, minimum_sampling_rate());
         mutex_unlock(&dbs_mutex);
 
@@ -250,7 +266,7 @@ static ssize_t store_up_threshold(struct cpufreq_policy *unused,
 
         mutex_lock(&dbs_mutex);
         if (ret != 1 || input > 100 ||
-            input <= dbs_tuners_ins.down_threshold) {
+                        input <= dbs_tuners_ins.down_threshold) {
                 mutex_unlock(&dbs_mutex);
                 return -EINVAL;
         }
@@ -269,7 +285,9 @@ static ssize_t store_down_threshold(struct cpufreq_policy *unused,
         ret = sscanf(buf, "%u", &input);
 
         mutex_lock(&dbs_mutex);
-        if (ret != 1 || input > 100 || input >= dbs_tuners_ins.up_threshold) {
+        /* cannot be lower than 11 otherwise freq will not fall */
+        if (ret != 1 || input < 11 || input > 100 ||
+                        input >= dbs_tuners_ins.up_threshold) {
                 mutex_unlock(&dbs_mutex);
                 return -EINVAL;
         }
@@ -302,12 +320,14 @@ static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
         }
         dbs_tuners_ins.ignore_nice = input;
 
-        /* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */
+        /* we need to re-evaluate prev_cpu_idle */
         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;
+                struct cpu_dbs_info_s *dbs_info;
+                dbs_info = &per_cpu(cpu_dbs_info, j);
+                dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
+                                                &dbs_info->prev_cpu_wall);
+                if (dbs_tuners_ins.ignore_nice)
+                        dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
         }
         mutex_unlock(&dbs_mutex);
 
@@ -319,7 +339,6 @@ static ssize_t store_freq_step(struct cpufreq_policy *policy,
 {
         unsigned int input;
         int ret;
-
         ret = sscanf(buf, "%u", &input);
 
         if (ret != 1)
@@ -367,55 +386,78 @@ static struct attribute_group dbs_attr_group = {
 
 /************************** sysfs end ************************/
 
-static void dbs_check_cpu(int cpu)
+static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 {
-        unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
-        unsigned int tmp_idle_ticks, total_idle_ticks;
+        unsigned int load = 0;
         unsigned int freq_target;
-        unsigned int freq_down_sampling_rate;
-        struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
-        struct cpufreq_policy *policy;
 
-        if (!this_dbs_info->enable)
-                return;
+        struct cpufreq_policy *policy;
+        unsigned int j;
 
         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 check, if current
+         * idle time is more than 80%, then we try to decrease frequency
          *
          * Any frequency increase takes it to the maximum frequency.
          * Frequency reduction happens at minimum steps of
-         * 5% (default) of max_frequency
+         * 5% (default) of maximum frequency
          */
 
-        /* Check for frequency increase */
-        idle_ticks = UINT_MAX;
+        /* Get Absolute Load */
+        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;
 
-        /* Check for frequency increase */
-        total_idle_ticks = get_cpu_idle_time(cpu);
-        tmp_idle_ticks = total_idle_ticks -
-                this_dbs_info->prev_cpu_idle_up;
-        this_dbs_info->prev_cpu_idle_up = total_idle_ticks;
+                j_dbs_info = &per_cpu(cpu_dbs_info, j);
+
+                cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
+
+                wall_time = (unsigned int) cputime64_sub(cur_wall_time,
+                                j_dbs_info->prev_cpu_wall);
+                j_dbs_info->prev_cpu_wall = cur_wall_time;
 
-        if (tmp_idle_ticks < idle_ticks)
-                idle_ticks = tmp_idle_ticks;
+                idle_time = (unsigned int) cputime64_sub(cur_idle_time,
+                                j_dbs_info->prev_cpu_idle);
+                j_dbs_info->prev_cpu_idle = cur_idle_time;
 
-        /* Scale idle ticks by 100 and compare with up and down ticks */
-        idle_ticks *= 100;
-        up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
-                        usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
+                if (dbs_tuners_ins.ignore_nice) {
+                        cputime64_t cur_nice;
+                        unsigned long cur_nice_jiffies;
+
+                        cur_nice = cputime64_sub(kstat_cpu(j).cpustat.nice,
+                                         j_dbs_info->prev_cpu_nice);
+                        /*
+                         * Assumption: nice time between sampling periods will
+                         * be less than 2^32 jiffies for 32 bit sys
+                         */
+                        cur_nice_jiffies = (unsigned long)
+                                        cputime64_to_jiffies64(cur_nice);
+
+                        j_dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
+                        idle_time += jiffies_to_usecs(cur_nice_jiffies);
+                }
+
+                if (unlikely(!wall_time || wall_time < idle_time))
+                        continue;
+
+                load = 100 * (wall_time - idle_time) / wall_time;
+        }
+
+        /*
+         * break out if we 'cannot' reduce the speed as the user might
+         * want freq_step to be zero
+         */
+        if (dbs_tuners_ins.freq_step == 0)
+                return;
 
-        if (idle_ticks < up_idle_ticks) {
+        /* Check for frequency increase */
+        if (load > dbs_tuners_ins.up_threshold) {
                 this_dbs_info->down_skip = 0;
-                this_dbs_info->prev_cpu_idle_down =
-                        this_dbs_info->prev_cpu_idle_up;
 
                 /* if we are already at full speed then break out early */
                 if (this_dbs_info->requested_freq == policy->max)
@@ -436,49 +478,24 @@ static void dbs_check_cpu(int cpu)
                 return;
         }
 
-        /* Check for frequency decrease */
-        this_dbs_info->down_skip++;
-        if (this_dbs_info->down_skip < dbs_tuners_ins.sampling_down_factor)
-                return;
-
-        /* Check for frequency decrease */
-        total_idle_ticks = this_dbs_info->prev_cpu_idle_up;
-        tmp_idle_ticks = total_idle_ticks -
-                this_dbs_info->prev_cpu_idle_down;
-        this_dbs_info->prev_cpu_idle_down = total_idle_ticks;
-
-        if (tmp_idle_ticks < idle_ticks)
-                idle_ticks = tmp_idle_ticks;
-
-        /* Scale idle ticks by 100 and compare with up and down ticks */
-        idle_ticks *= 100;
-        this_dbs_info->down_skip = 0;
-
-        freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
-                dbs_tuners_ins.sampling_down_factor;
-        down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) *
-                usecs_to_jiffies(freq_down_sampling_rate);
-
-        if (idle_ticks > down_idle_ticks) {
-                /*
-                 * if we are already at the lowest speed then break out early
-                 * or if we 'cannot' reduce the speed as the user might want
-                 * freq_target to be zero
-                 */
-                if (this_dbs_info->requested_freq == policy->min
-                                || dbs_tuners_ins.freq_step == 0)
-                        return;
-
+        /*
+         * 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.
+         */
+        if (load < (dbs_tuners_ins.down_threshold - 10)) {
                 freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100;
 
-                /* max freq cannot be less than 100. But who knows.... */
-                if (unlikely(freq_target == 0))
-                        freq_target = 5;
-
                 this_dbs_info->requested_freq -= freq_target;
                 if (this_dbs_info->requested_freq < policy->min)
                         this_dbs_info->requested_freq = policy->min;
 
+                /*
+                 * if we cannot reduce the frequency anymore, break out early
+                 */
+                if (policy->cur == policy->min)
+                        return;
+
                 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
                                 CPUFREQ_RELATION_H);
                 return;
@@ -487,27 +504,45 @@ static void dbs_check_cpu(int cpu)
 
 static void do_dbs_timer(struct work_struct *work)
 {
-        int i;
-        mutex_lock(&dbs_mutex);
-        for_each_online_cpu(i)
-                dbs_check_cpu(i);
-        schedule_delayed_work(&dbs_work,
-                        usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
-        mutex_unlock(&dbs_mutex);
+        struct cpu_dbs_info_s *dbs_info =
+                container_of(work, struct cpu_dbs_info_s, work.work);
+        unsigned int cpu = dbs_info->cpu;
+
+        /* We want all CPUs to do sampling nearly on same jiffy */
+        int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
+
+        delay -= jiffies % delay;
+
+        if (lock_policy_rwsem_write(cpu) < 0)
+                return;
+
+        if (!dbs_info->enable) {
+                unlock_policy_rwsem_write(cpu);
+                return;
+        }
+
+        dbs_check_cpu(dbs_info);
+
+        queue_delayed_work_on(cpu, kconservative_wq, &dbs_info->work, delay);
+        unlock_policy_rwsem_write(cpu);
 }
 
-static inline void dbs_timer_init(void)
+static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
 {
-        init_timer_deferrable(&dbs_work.timer);
-        schedule_delayed_work(&dbs_work,
-                        usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
-        return;
+        /* We want all CPUs to do sampling nearly on same jiffy */
+        int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
+        delay -= jiffies % delay;
+
+        dbs_info->enable = 1;
+        INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
+        queue_delayed_work_on(dbs_info->cpu, kconservative_wq, &dbs_info->work,
+                                delay);
 }
 
-static inline void dbs_timer_exit(void)
+static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
 {
-        cancel_delayed_work(&dbs_work);
-        return;
+        dbs_info->enable = 0;
+        cancel_delayed_work(&dbs_info->work);
 }
 
 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
@@ -541,11 +576,13 @@ 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 = get_cpu_idle_time(cpu);
-                        j_dbs_info->prev_cpu_idle_down
-                                = j_dbs_info->prev_cpu_idle_up;
+                        j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
+                                                &j_dbs_info->prev_cpu_wall);
+                        if (dbs_tuners_ins.ignore_nice) {
+                                j_dbs_info->prev_cpu_nice =
+                                                kstat_cpu(j).cpustat.nice;
+                        }
                 }
-                this_dbs_info->enable = 1;
                 this_dbs_info->down_skip = 0;
                 this_dbs_info->requested_freq = policy->cur;
 
@@ -567,30 +604,30 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 
                         dbs_tuners_ins.sampling_rate = def_sampling_rate;
 
-                        dbs_timer_init();
                         cpufreq_register_notifier(
                                         &dbs_cpufreq_notifier_block,
                                         CPUFREQ_TRANSITION_NOTIFIER);
                 }
+                dbs_timer_init(this_dbs_info);
 
                 mutex_unlock(&dbs_mutex);
+
                 break;
 
         case CPUFREQ_GOV_STOP:
                 mutex_lock(&dbs_mutex);
-                this_dbs_info->enable = 0;
+                dbs_timer_exit(this_dbs_info);
                 sysfs_remove_group(&policy->kobj, &dbs_attr_group);
                 dbs_enable--;
+
                 /*
                  * Stop the timerschedule work, when this governor
                  * is used for first time
                  */
-                if (dbs_enable == 0) {
-                        dbs_timer_exit();
+                if (dbs_enable == 0)
                         cpufreq_unregister_notifier(
                                         &dbs_cpufreq_notifier_block,
                                         CPUFREQ_TRANSITION_NOTIFIER);
-                }
 
                 mutex_unlock(&dbs_mutex);
 
@@ -607,6 +644,7 @@ static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
                                         this_dbs_info->cur_policy,
                                         policy->min, CPUFREQ_RELATION_L);
                 mutex_unlock(&dbs_mutex);
+
                 break;
         }
         return 0;
@@ -624,15 +662,25 @@ struct cpufreq_governor cpufreq_gov_conservative = {
 
 static int __init cpufreq_gov_dbs_init(void)
 {
-        return cpufreq_register_governor(&cpufreq_gov_conservative);
+        int err;
+
+        kconservative_wq = create_workqueue("kconservative");
+        if (!kconservative_wq) {
+                printk(KERN_ERR "Creation of kconservative failed\n");
+                return -EFAULT;
+        }
+
+        err = cpufreq_register_governor(&cpufreq_gov_conservative);
+        if (err)
+                destroy_workqueue(kconservative_wq);
+
+        return err;
 }
 
 static void __exit cpufreq_gov_dbs_exit(void)
 {
-        /* Make sure that the scheduled work is indeed not running */
-        flush_scheduled_work();
-
         cpufreq_unregister_governor(&cpufreq_gov_conservative);
+        destroy_workqueue(kconservative_wq);
 }