[PATCH] cpufreq_ondemand tweaks (round two)

From: Alexander Clouter
Date: Sun Nov 07 2004 - 03:37:07 EST

Hi All,

After listening to all your points a couple of weeks back I found the time to
break up my patches to 'ondemand' into three smaller patches and my clean my
tweaks up a little. I also went ahead with the suggestion to create a
completely new governor ('conservative', better name suggestions welcome)
which has the major alteration so that the change in frequency is made
gradually in both directions; this, I feel, being much more suitable for
battery powered environments.

I also included the relevant cleanup code by Adrian Bunk ([2.6 patch] small
cpufreq cleanup 2004-10-30 7:22:46) into the conservative governor.

As a side note, Venkatesh might want to consider dropping the default
sampling rate an order of magnitude as on my laptop its constantly flicking
between min and max and is a bit too trigger happy whilst the cpu use at
around 5%; for me at least. Bruno Ducrot pointed out that the amd64's "do
have unacceptable latency between min and max freq transition, due to the
step-by-step requirements (200MHz IIRC)". For me its just a a cosmetic
annoyance in /proc/cpuinfo :)

Let me know what you think.

Regards

Alex

------------------------------------------
01_ignore-nice.diff
-------------------
Adds support so that you can choose to consider (default) or ignore 'nice'ed
processes.

02_check-rate-and-break-out.diff
--------------------------------
If it is decided that cpu needs to be sped up a notch but yet the cpu frequency
is already at max (or reduce speed but already at its lowest frequency) then we
break out without wasting cpu cycles and (possible?) latency issues attempting
to make changes that have no effect.

03_sys_freq_step.diff
---------------------
the step down frequency is now tweakable through /sys. It takes an unsigned int
between zero and (((max - min) * 100) / max), the percentage equal to the
difference between min and max. The advantage of this is that all the divisions
are moved out of the main loop when it comes to working out whas frequency in
khz the cpu should be lowered by.
------------------------------

--
________________________________________
/ Nullum magnum ingenium sine mixtura \
| dementiae fuit. |
| |
| [There is no great genius without some |
| touch of madness.] |
| |
\ -- Seneca /
----------------------------------------
\ ^__^
\ (oo)\_______
(__)\ )\/\
||----w |
|| ||
diff -u -U 2 -r -N -d linux-2.6.9.orig/drivers/cpufreq/cpufreq_ondemand.c linux-2.6.9/drivers/cpufreq/cpufreq_ondemand.c
--- linux-2.6.9.orig/drivers/cpufreq/cpufreq_ondemand.c 2004-10-18 22:55:27.000000000 +0100
+++ linux-2.6.9/drivers/cpufreq/cpufreq_ondemand.c 2004-11-06 13:08:46.000000000 +0000
@@ -81,6 +81,7 @@
unsigned int sampling_down_factor;
unsigned int up_threshold;
unsigned int down_threshold;
+ unsigned int ignore_nice;
};

struct dbs_tuners dbs_tuners_ins = {
@@ -120,6 +121,7 @@
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)
@@ -189,6 +191,22 @@
return count;
}

+static ssize_t store_ignore_nice(struct cpufreq_policy *unused,
+ const char *buf, size_t count)
+{
+ unsigned int input;
+ int ret;
+ ret = sscanf (buf, "%u", &input);
+ down(&dbs_sem);
+ if ( ret == 1 ) {
+ if ( input > 1 )
+ input = 1;
+ dbs_tuners_ins.ignore_nice = input;
+ }
+ up(&dbs_sem);
+ return count;
+}
+
#define define_one_rw(_name) \
static struct freq_attr _name = { \
.attr = { .name = __stringify(_name), .mode = 0644 }, \
@@ -200,6 +218,7 @@
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,
@@ -208,6 +227,7 @@
&sampling_down_factor.attr,
&up_threshold.attr,
&down_threshold.attr,
+ &ignore_nice.attr,
NULL
};

@@ -247,6 +267,10 @@
/* Check for frequency increase */
total_idle_ticks = kstat_cpu(cpu).cpustat.idle +
kstat_cpu(cpu).cpustat.iowait;
+ /* consider 'nice' tasks as 'idle' time too if required */
+ if (dbs_tuners_ins.ignore_nice == 0)
+ total_idle_ticks += kstat_cpu(cpu).cpustat.nice;
+
idle_ticks = total_idle_ticks -
this_dbs_info->prev_cpu_idle_up;
this_dbs_info->prev_cpu_idle_up = total_idle_ticks;
@@ -346,10 +370,12 @@

this_dbs_info->prev_cpu_idle_up =
kstat_cpu(cpu).cpustat.idle +
- kstat_cpu(cpu).cpustat.iowait;
+ kstat_cpu(cpu).cpustat.iowait +
+ kstat_cpu(cpu).cpustat.nice;
this_dbs_info->prev_cpu_idle_down =
kstat_cpu(cpu).cpustat.idle +
- kstat_cpu(cpu).cpustat.iowait;
+ kstat_cpu(cpu).cpustat.iowait +
+ kstat_cpu(cpu).cpustat.nice;
this_dbs_info->enable = 1;
sysfs_create_group(&policy->kobj, &dbs_attr_group);
dbs_enable++;
@@ -368,6 +394,7 @@
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();
}
--- linux-2.6.9.orig/drivers/cpufreq/cpufreq_ondemand.c 2004-11-06 22:13:49.000000000 +0000
+++ linux-2.6.9/drivers/cpufreq/cpufreq_ondemand.c 2004-11-06 22:13:16.000000000 +0000
@@ -281,6 +281,9 @@
sampling_rate_in_HZ(dbs_tuners_ins.sampling_rate);

if (idle_ticks < up_idle_ticks) {
+ if (this_dbs_info->cur_policy->cur
+ == this_dbs_info->cur_policy->max)
+ return;
__cpufreq_driver_target(this_dbs_info->cur_policy,
this_dbs_info->cur_policy->max,
CPUFREQ_RELATION_H);
@@ -307,6 +310,9 @@
sampling_rate_in_HZ(freq_down_sampling_rate);

if (idle_ticks > down_idle_ticks ) {
+ if (this_dbs_info->cur_policy->cur
+ == this_dbs_info->cur_policy->min)
+ return;
freq_down_step = (5 * this_dbs_info->cur_policy->max) / 100;

/* max freq cannot be less than 100. But who knows.... */
--- linux-2.6.9.orig/drivers/cpufreq/cpufreq_ondemand.c 2004-11-06 23:15:57.000000000 +0000
+++ linux-2.6.9/drivers/cpufreq/cpufreq_ondemand.c 2004-11-06 23:16:20.000000000 +0000
@@ -82,6 +82,7 @@
unsigned int up_threshold;
unsigned int down_threshold;
unsigned int ignore_nice;
+ unsigned int freq_step;
};

struct dbs_tuners dbs_tuners_ins = {
@@ -123,6 +124,13 @@
show_one(down_threshold, down_threshold);
show_one(ignore_nice, ignore_nice);

+static ssize_t show_freq_step(struct cpufreq_policy *policy, char *buf)
+{
+ unsigned int percent = (dbs_tuners_ins.freq_step * 100) / policy->max;
+
+ return sprintf (buf, "%u\n", percent);
+}
+
static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
const char *buf, size_t count)
{
@@ -207,6 +215,29 @@
return count;
}

+static ssize_t store_freq_step(struct cpufreq_policy *policy,
+ const char *buf, size_t count)
+{
+ unsigned int input;
+ int ret;
+ unsigned int freq_step = dbs_tuners_ins.freq_step;
+ ret = sscanf (buf, "%u", &input);
+ down(&dbs_sem);
+ if ( ret == 1 ) {
+ if (input > (((policy->max - policy->min) * 100)
+ / policy->max)) {
+ freq_step = policy->max - policy->min;
+ } else {
+ /* no need to test here if freq_step is zero as the user
+ * might actually want this */
+ freq_step = (input * policy->max) / 100;
+ }
+ dbs_tuners_ins.freq_step = freq_step;
+ }
+ up(&dbs_sem);
+ return count;
+}
+
#define define_one_rw(_name) \
static struct freq_attr _name = { \
.attr = { .name = __stringify(_name), .mode = 0644 }, \
@@ -219,6 +250,7 @@
define_one_rw(up_threshold);
define_one_rw(down_threshold);
define_one_rw(ignore_nice);
+define_one_rw(freq_step);

static struct attribute * dbs_attributes[] = {
&sampling_rate_max.attr,
@@ -228,6 +260,7 @@
&up_threshold.attr,
&down_threshold.attr,
&ignore_nice.attr,
+ &freq_step.attr,
NULL
};

@@ -242,7 +275,6 @@
{
unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
unsigned int total_idle_ticks;
- unsigned int freq_down_step;
unsigned int freq_down_sampling_rate;
static int down_skip[NR_CPUS];
struct cpu_dbs_info_s *this_dbs_info;
@@ -262,7 +294,7 @@
*
* Any frequency increase takes it to the maximum frequency.
* Frequency reduction happens at minimum steps of
- * 5% of max_frequency
+ * 5% (default) of max_frequency
*/
/* Check for frequency increase */
total_idle_ticks = kstat_cpu(cpu).cpustat.idle +
@@ -313,14 +345,10 @@
if (this_dbs_info->cur_policy->cur
== this_dbs_info->cur_policy->min)
return;
- freq_down_step = (5 * this_dbs_info->cur_policy->max) / 100;
-
- /* max freq cannot be less than 100. But who knows.... */
- if (unlikely(freq_down_step == 0))
- freq_down_step = 5;

__cpufreq_driver_target(this_dbs_info->cur_policy,
- this_dbs_info->cur_policy->cur - freq_down_step,
+ this_dbs_info->cur_policy->cur
+ - dbs_tuners_ins.freq_step,
CPUFREQ_RELATION_H);
return;
}
@@ -401,7 +429,12 @@
DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
dbs_tuners_ins.sampling_rate = def_sampling_rate;
dbs_tuners_ins.ignore_nice = 0;
-
+ dbs_tuners_ins.freq_step = (5 * policy->max ) / 100;
+
+ /* max freq cannot be less than 100. But who knows... */
+ if (unlikely(dbs_tuners_ins.freq_step == 0))
+ dbs_tuners_ins.freq_step = 5;
+
dbs_timer_init();
}

diff -u -U 2 -r -N -d linux-2.6.9.orig/drivers/cpufreq/cpufreq_conservative.c linux-2.6.9/drivers/cpufreq/cpufreq_conservative.c
--- linux-2.6.9.orig/drivers/cpufreq/cpufreq_conservative.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.9/drivers/cpufreq/cpufreq_conservative.c 2004-11-07 08:05:56.000000000 +0000
@@ -0,0 +1,525 @@
+/*
+ * drivers/cpufreq/cpufreq_conservative.c
+ *
+ * Copyright (C) 2001 Russell King
+ * (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>.
+ * Jun Nakajima <jun.nakajima@xxxxxxxxx>
+ * (C) 2004 Alexander Clouter <alex-kernel@xxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/config.h>
+#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/sched.h>
+#include <linux/kmod.h>
+#include <linux/workqueue.h>
+#include <linux/jiffies.h>
+#include <linux/config.h>
+#include <linux/kernel_stat.h>
+#include <linux/percpu.h>
+
+/*
+ * dbs is used in this file as a shortform for demandbased switching
+ * It helps to keep variable names smaller, simpler
+ */
+
+#define DEF_FREQUENCY_UP_THRESHOLD (80)
+#define MIN_FREQUENCY_UP_THRESHOLD (0)
+#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 50000 times the transition
+ * 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.
+ * All times here are in uS.
+ */
+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 (5)
+#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);
+
+struct cpu_dbs_info_s {
+ struct cpufreq_policy *cur_policy;
+ unsigned int prev_cpu_ticks;
+ unsigned int prev_cpu_idle_ticks;
+ unsigned int enable;
+};
+static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
+
+static unsigned int dbs_enable; /* number of CPUs using this policy */
+
+static DECLARE_MUTEX (dbs_sem);
+static DECLARE_WORK (dbs_work, do_dbs_timer, NULL);
+
+struct dbs_tuners {
+ unsigned int sampling_rate;
+ unsigned int sampling_down_factor;
+ unsigned int up_threshold;
+ unsigned int down_threshold;
+ unsigned int requested_freq;
+ unsigned int ignore_nice;
+ unsigned int freq_step;
+};
+
+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,
+};
+
+/************************** sysfs interface ************************/
+static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
+{
+ return sprintf (buf, "%u\n", MAX_SAMPLING_RATE);
+}
+
+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 = { \
+ .attr = { .name = __stringify(_name), .mode = 0444 }, \
+ .show = show_##_name, \
+}
+
+define_one_ro(sampling_rate_max);
+define_one_ro(sampling_rate_min);
+
+/* cpufreq_conservative Governor Tunables */
+#define show_one(file_name, object) \
+static ssize_t show_##file_name \
+(struct cpufreq_policy *unused, char *buf) \
+{ \
+ return sprintf(buf, "%u\n", dbs_tuners_ins.object); \
+}
+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 show_freq_step(struct cpufreq_policy *policy, char *buf)
+{
+ unsigned int percent = (dbs_tuners_ins.freq_step * 100) / policy->max;
+
+ return sprintf (buf, "%u\n", percent);
+}
+
+static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
+ const char *buf, size_t count)
+{
+ unsigned int input;
+ int ret;
+ ret = sscanf (buf, "%u", &input);
+ down(&dbs_sem);
+ if (ret != 1 )
+ goto out;
+
+ dbs_tuners_ins.sampling_down_factor = input;
+out:
+ up(&dbs_sem);
+ return count;
+}
+
+static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
+ const char *buf, size_t count)
+{
+ unsigned int input;
+ int ret;
+ ret = sscanf (buf, "%u", &input);
+ down(&dbs_sem);
+ if (ret != 1 || input > MAX_SAMPLING_RATE || input < MIN_SAMPLING_RATE)
+ goto out;
+
+ dbs_tuners_ins.sampling_rate = input;
+out:
+ up(&dbs_sem);
+ return count;
+}
+
+static ssize_t store_up_threshold(struct cpufreq_policy *unused,
+ const char *buf, size_t count)
+{
+ unsigned int input;
+ int ret;
+ ret = sscanf (buf, "%u", &input);
+ down(&dbs_sem);
+ if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
+ input < MIN_FREQUENCY_UP_THRESHOLD ||
+ input <= dbs_tuners_ins.down_threshold)
+ goto out;
+
+ dbs_tuners_ins.up_threshold = input;
+out:
+ up(&dbs_sem);
+ return count;
+}
+
+static ssize_t store_down_threshold(struct cpufreq_policy *unused,
+ const char *buf, size_t count)
+{
+ unsigned int input;
+ int ret;
+ ret = sscanf (buf, "%u", &input);
+ down(&dbs_sem);
+ if (ret != 1 || input > MAX_FREQUENCY_DOWN_THRESHOLD ||
+ input < MIN_FREQUENCY_DOWN_THRESHOLD ||
+ input >= dbs_tuners_ins.up_threshold)
+ goto out;
+
+ dbs_tuners_ins.down_threshold = input;
+out:
+ up(&dbs_sem);
+ return count;
+}
+
+static ssize_t store_ignore_nice(struct cpufreq_policy *unused,
+ const char *buf, size_t count)
+{
+ unsigned int input;
+ int ret;
+ ret = sscanf (buf, "%u", &input);
+ down(&dbs_sem);
+ if ( ret == 1 ) {
+ if ( input > 1 )
+ input = 1;
+ dbs_tuners_ins.ignore_nice = input;
+ }
+ up(&dbs_sem);
+ return count;
+}
+
+static ssize_t store_freq_step(struct cpufreq_policy *policy,
+ const char *buf, size_t count)
+{
+ unsigned int input;
+ int ret;
+ unsigned int freq_step = dbs_tuners_ins.freq_step;
+ ret = sscanf (buf, "%u", &input);
+ down(&dbs_sem);
+ if ( ret == 1 ) {
+ if (input > (((policy->max - policy->min) * 100)
+ / policy->max)) {
+ freq_step = policy->max - policy->min;
+ } else {
+ /* no need to test here if freq_step is zero as the user
+ * might actually want this */
+ freq_step = (input * policy->max) / 100;
+ }
+ dbs_tuners_ins.freq_step = freq_step;
+ }
+ up(&dbs_sem);
+ return count;
+}
+
+#define define_one_rw(_name) \
+static struct freq_attr _name = { \
+ .attr = { .name = __stringify(_name), .mode = 0644 }, \
+ .show = show_##_name, \
+ .store = 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);
+define_one_rw(freq_step);
+
+static struct attribute * dbs_attributes[] = {
+ &sampling_rate_max.attr,
+ &sampling_rate_min.attr,
+ &sampling_rate.attr,
+ &sampling_down_factor.attr,
+ &up_threshold.attr,
+ &down_threshold.attr,
+ &ignore_nice.attr,
+ &freq_step.attr,
+ NULL
+};
+
+static struct attribute_group dbs_attr_group = {
+ .attrs = dbs_attributes,
+ .name = "conservative",
+};
+
+/************************** sysfs end ************************/
+
+static void dbs_check_cpu(int cpu)
+{
+ unsigned int total_ticks, total_idle_ticks;
+ unsigned int ticks, idle_ticks;
+ static int down_skip[NR_CPUS];
+ struct cpu_dbs_info_s *this_dbs_info;
+
+ this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
+ if (!this_dbs_info->enable)
+ return;
+
+ /*
+ * 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
+ *
+ * Any frequency increase takes it to the maximum frequency.
+ * Frequency reduction happens at minimum steps of
+ * 5% (default) of max_frequency
+ *
+ * My modified routine compares the number of idle ticks with the
+ * expected number of idle ticks for the boundaries and acts accordingly
+ * - Alex
+ */
+ total_ticks =
+ kstat_cpu(cpu).cpustat.user +
+ kstat_cpu(cpu).cpustat.nice +
+ kstat_cpu(cpu).cpustat.system +
+ kstat_cpu(cpu).cpustat.softirq +
+ kstat_cpu(cpu).cpustat.irq +
+ kstat_cpu(cpu).cpustat.idle +
+ kstat_cpu(cpu).cpustat.iowait;
+ total_idle_ticks =
+ kstat_cpu(cpu).cpustat.idle +
+ kstat_cpu(cpu).cpustat.iowait;
+ /* consider 'nice' tasks as 'idle' time too if required */
+ if (dbs_tuners_ins.ignore_nice == 0)
+ total_idle_ticks += kstat_cpu(cpu).cpustat.nice;
+
+ ticks = (total_ticks -
+ this_dbs_info->prev_cpu_ticks) * 100;
+ idle_ticks = (total_idle_ticks -
+ this_dbs_info->prev_cpu_idle_ticks) * 100;
+
+ this_dbs_info->prev_cpu_ticks = total_ticks;
+ this_dbs_info->prev_cpu_idle_ticks = total_idle_ticks;
+
+ /* nothing to do if we cannot shift the frequency */
+ if (dbs_tuners_ins.freq_step == 0)
+ return;
+
+ if ((ticks - idle_ticks)
+ > (dbs_tuners_ins.up_threshold * idle_ticks)) {
+ if (this_dbs_info->cur_policy->cur
+ == this_dbs_info->cur_policy->max)
+ return;
+
+ dbs_tuners_ins.requested_freq += dbs_tuners_ins.freq_step;
+ if (dbs_tuners_ins.requested_freq >
+ this_dbs_info->cur_policy->max)
+ dbs_tuners_ins.requested_freq =
+ this_dbs_info->cur_policy->max;
+
+ __cpufreq_driver_target(this_dbs_info->cur_policy,
+ dbs_tuners_ins.requested_freq, CPUFREQ_RELATION_H);
+ down_skip[cpu] = 0;
+ return;
+ }
+
+ /* Check for frequency decrease */
+ down_skip[cpu]++;
+ if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor)
+ return;
+
+ if ((ticks - idle_ticks)
+ < (dbs_tuners_ins.down_threshold * idle_ticks)) {
+ if (this_dbs_info->cur_policy->cur
+ == this_dbs_info->cur_policy->min)
+ return;
+
+ dbs_tuners_ins.requested_freq -= dbs_tuners_ins.freq_step;
+ if (dbs_tuners_ins.requested_freq <
+ this_dbs_info->cur_policy->min)
+ dbs_tuners_ins.requested_freq =
+ this_dbs_info->cur_policy->min;
+
+ __cpufreq_driver_target(this_dbs_info->cur_policy,
+ dbs_tuners_ins.requested_freq, CPUFREQ_RELATION_H);
+ down_skip[cpu] = 0;
+ return;
+ }
+}
+
+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);
+ schedule_delayed_work(&dbs_work,
+ sampling_rate_in_HZ(dbs_tuners_ins.sampling_rate));
+ up(&dbs_sem);
+}
+
+static inline void dbs_timer_init(void)
+{
+ INIT_WORK(&dbs_work, do_dbs_timer, NULL);
+ schedule_work(&dbs_work);
+ return;
+}
+
+static inline void dbs_timer_exit(void)
+{
+ cancel_delayed_work(&dbs_work);
+ return;
+}
+
+static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
+ unsigned int event)
+{
+ unsigned int cpu = policy->cpu;
+ struct cpu_dbs_info_s *this_dbs_info;
+
+ this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
+
+ switch (event) {
+ case CPUFREQ_GOV_START:
+ if ((!cpu_online(cpu)) ||
+ (!policy->cur))
+ return -EINVAL;
+
+ if (policy->cpuinfo.transition_latency >
+ (TRANSITION_LATENCY_LIMIT * 1000))
+ return -EINVAL;
+ if (this_dbs_info->enable) /* Already enabled */
+ break;
+
+ down(&dbs_sem);
+ this_dbs_info->cur_policy = policy;
+
+ this_dbs_info->prev_cpu_ticks =
+ kstat_cpu(cpu).cpustat.user +
+ kstat_cpu(cpu).cpustat.nice +
+ kstat_cpu(cpu).cpustat.system +
+ kstat_cpu(cpu).cpustat.softirq +
+ kstat_cpu(cpu).cpustat.irq +
+ kstat_cpu(cpu).cpustat.idle +
+ kstat_cpu(cpu).cpustat.iowait;
+ this_dbs_info->prev_cpu_idle_ticks =
+ kstat_cpu(cpu).cpustat.idle +
+ kstat_cpu(cpu).cpustat.iowait +
+ kstat_cpu(cpu).cpustat.nice;
+ this_dbs_info->enable = 1;
+ sysfs_create_group(&policy->kobj, &dbs_attr_group);
+ dbs_enable++;
+ /*
+ * Start the timerschedule work, when this governor
+ * is used for first time
+ */
+ if (dbs_enable == 1) {
+ unsigned int latency;
+ /* policy latency is in nS. Convert it to uS first */
+
+ latency = policy->cpuinfo.transition_latency;
+ if (latency < 1000)
+ latency = 1000;
+
+ def_sampling_rate = (latency / 10) *
+ DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
+ dbs_tuners_ins.sampling_rate = def_sampling_rate;
+ dbs_tuners_ins.requested_freq
+ = this_dbs_info->cur_policy->cur;
+ dbs_tuners_ins.ignore_nice = 0;
+ dbs_tuners_ins.freq_step = (5 * policy->max ) / 100;
+
+ /* max freq cannot be less than 100. But who knows... */
+ if (unlikely(dbs_tuners_ins.freq_step == 0))
+ dbs_tuners_ins.freq_step = 5;
+
+ dbs_timer_init();
+ }
+
+ up(&dbs_sem);
+ break;
+
+ case CPUFREQ_GOV_STOP:
+ down(&dbs_sem);
+ this_dbs_info->enable = 0;
+ 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();
+
+ up(&dbs_sem);
+
+ break;
+
+ case CPUFREQ_GOV_LIMITS:
+ down(&dbs_sem);
+ if (policy->max < this_dbs_info->cur_policy->cur)
+ __cpufreq_driver_target(
+ this_dbs_info->cur_policy,
+ policy->max, CPUFREQ_RELATION_H);
+ else if (policy->min > this_dbs_info->cur_policy->cur)
+ __cpufreq_driver_target(
+ this_dbs_info->cur_policy,
+ policy->min, CPUFREQ_RELATION_L);
+ up(&dbs_sem);
+ break;
+ }
+ return 0;
+}
+
+static struct cpufreq_governor cpufreq_gov_dbs = {
+ .name = "conservative",
+ .governor = cpufreq_governor_dbs,
+ .owner = THIS_MODULE,
+};
+
+static int __init cpufreq_gov_dbs_init(void)
+{
+ return cpufreq_register_governor(&cpufreq_gov_dbs);
+}
+
+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_dbs);
+}
+
+
+MODULE_AUTHOR ("Alexander Clouter <alex-kernel@xxxxxxxxxxxxx>");
+MODULE_DESCRIPTION ("'cpufreq_conservative' - A dynamic cpufreq governor for "
+ "Low Latency Frequency Transition capable processors "
+ "optimised for use in a battery environment");
+MODULE_LICENSE ("GPL");
+
+module_init(cpufreq_gov_dbs_init);
+module_exit(cpufreq_gov_dbs_exit);
diff -u -U 2 -r -N -d linux-2.6.9.orig/drivers/cpufreq/Kconfig linux-2.6.9/drivers/cpufreq/Kconfig
--- linux-2.6.9.orig/drivers/cpufreq/Kconfig 2004-10-18 22:55:07.000000000 +0100
+++ linux-2.6.9/drivers/cpufreq/Kconfig 2004-11-07 00:34:25.000000000 +0000
@@ -84,6 +84,24 @@

If in doubt, say N.

+config CPU_FREQ_GOV_CONSERVATIVE
+ tristate "'conservative' cpufreq policy governor"
+ depends on CPU_FREQ
+ help
+ 'conservative' - this driver is quite identical to the 'ondemand'
+ governor both in its source code and purpose, the difference is that
+ it has been designed to be much more suitable in a battery powered
+ environment. The frequency is gracefully increased and decreased
+ rather than jumping to 100% when speed is required and dropping back
+ aggressively. It also polls 100 times fewer times than 'ondemand'.
+
+ For details, take a look at linux/Documentation/cpu-freq.
+
+ If you have a desktop machine then you should consider really the
+ 'ondemand' governor instead, however if you are using a laptop, PDA or
+ even an AMD64 based desktop (due to latency issues) you probably will
+ want to use this governor. If in doubt, say N.
+
config CPU_FREQ_24_API
bool "/proc/sys/cpu/ interface (2.4. / OLD)"
depends on CPU_FREQ && SYSCTL && CPU_FREQ_GOV_USERSPACE
diff -u -U 2 -r -N -d linux-2.6.9.orig/drivers/cpufreq/Makefile linux-2.6.9/drivers/cpufreq/Makefile
--- linux-2.6.9.orig/drivers/cpufreq/Makefile 2004-10-18 22:55:36.000000000 +0100
+++ linux-2.6.9/drivers/cpufreq/Makefile 2004-11-06 23:39:41.000000000 +0000
@@ -6,6 +6,7 @@
obj-$(CONFIG_CPU_FREQ_GOV_POWERSAVE) += cpufreq_powersave.o
obj-$(CONFIG_CPU_FREQ_GOV_USERSPACE) += cpufreq_userspace.o
obj-$(CONFIG_CPU_FREQ_GOV_ONDEMAND) += cpufreq_ondemand.o
+obj-$(CONFIG_CPU_FREQ_GOV_CONSERVATIVE) += cpufreq_conservative.o

# CPUfreq cross-arch helpers
obj-$(CONFIG_CPU_FREQ_TABLE) += freq_table.o

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