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[CPUFREQ] Remove slowdown from ondemand sampling path.

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Remove slowdown from ondemand sampling path. This reduces the code path length
in dbs_check_cpu() by half. slowdown was not used by ondemand by default.
If there are any user level tools that were using this tunable, they
may report error now.

Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Dave Jones <davej@redhat.com>
This commit is contained in:
Venkatesh Pallipadi 2006-06-28 13:49:52 -07:00 committed by Dave Jones
parent 501b7c77de
commit ccb2fe209d
2 changed files with 42 additions and 98 deletions
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138
drivers/cpufreq/cpufreq_ondemand.c
View file

@ -56,16 +56,14 @@ static unsigned int def_sampling_rate;
#define MIN_SAMPLING_RATE (def_sampling_rate / MIN_SAMPLING_RATE_RATIO)
#define MAX_SAMPLING_RATE (500 * def_sampling_rate)
#define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER (1000)
#define DEF_SAMPLING_DOWN_FACTOR (1)
#define MAX_SAMPLING_DOWN_FACTOR (10)
#define TRANSITION_LATENCY_LIMIT (10 * 1000)
static void do_dbs_timer(void *data);
struct cpu_dbs_info_s {
cputime64_t prev_cpu_idle;
cputime64_t prev_cpu_wall;
struct cpufreq_policy *cur_policy;
unsigned int prev_cpu_idle_up;
unsigned int prev_cpu_idle_down;
unsigned int enable;
};
static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
@ -87,24 +85,26 @@ static struct workqueue_struct *dbs_workq;
struct dbs_tuners {
unsigned int sampling_rate;
unsigned int sampling_down_factor;
unsigned int up_threshold;
unsigned int ignore_nice;
};
static struct dbs_tuners dbs_tuners_ins = {
.up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
.sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
.ignore_nice = 0,
};
static inline unsigned int get_cpu_idle_time(unsigned int cpu)
static inline cputime64_t 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);
cputime64_t retval;
retval = cputime64_add(kstat_cpu(cpu).cpustat.idle,
kstat_cpu(cpu).cpustat.iowait);
if (dbs_tuners_ins.ignore_nice)
retval = cputime64_add(retval, kstat_cpu(cpu).cpustat.nice);
return retval;
}
/************************** sysfs interface ************************/
@ -133,29 +133,9 @@ static ssize_t show_##file_name \
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(ignore_nice_load, ignore_nice);
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);
if (ret != 1 )
return -EINVAL;
if (input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
return -EINVAL;
mutex_lock(&dbs_mutex);
dbs_tuners_ins.sampling_down_factor = input;
mutex_unlock(&dbs_mutex);
return count;
}
static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
const char *buf, size_t count)
{
@ -217,12 +197,12 @@ 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 = get_jiffies_64();
}
mutex_unlock(&dbs_mutex);
@ -234,7 +214,6 @@ static struct freq_attr _name = \
__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(ignore_nice_load);
@ -242,7 +221,6 @@ static struct attribute * dbs_attributes[] = {
&sampling_rate_max.attr,
&sampling_rate_min.attr,
&sampling_rate.attr,
&sampling_down_factor.attr,
&up_threshold.attr,
&ignore_nice_load.attr,
NULL
@ -257,11 +235,10 @@ static struct attribute_group dbs_attr_group = {
static void dbs_check_cpu(int cpu)
{
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];
unsigned int idle_ticks, total_ticks;
unsigned int load;
struct cpu_dbs_info_s *this_dbs_info;
cputime64_t cur_jiffies;
struct cpufreq_policy *policy;
unsigned int j;
@ -271,10 +248,14 @@ static void dbs_check_cpu(int cpu)
return;
policy = this_dbs_info->cur_policy;
cur_jiffies = jiffies64_to_cputime64(get_jiffies_64());
total_ticks = (unsigned int) cputime64_sub(cur_jiffies,
this_dbs_info->prev_cpu_wall);
this_dbs_info->prev_cpu_wall = cur_jiffies;
/*
* 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
* Every sampling_rate, 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.
*
@ -283,36 +264,26 @@ static void dbs_check_cpu(int cpu)
* 5% (default) of current frequency
*/
/* Check for frequency increase */
/* Get Idle Time */
idle_ticks = UINT_MAX;
for_each_cpu_mask(j, policy->cpus) {
unsigned int tmp_idle_ticks, total_idle_ticks;
cputime64_t total_idle_ticks;
unsigned int tmp_idle_ticks;
struct cpu_dbs_info_s *j_dbs_info;
j_dbs_info = &per_cpu(cpu_dbs_info, j);
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;
tmp_idle_ticks = (unsigned int) cputime64_sub(total_idle_ticks,
j_dbs_info->prev_cpu_idle);
j_dbs_info->prev_cpu_idle = total_idle_ticks;
if (tmp_idle_ticks < idle_ticks)
idle_ticks = tmp_idle_ticks;
}
load = (100 * (total_ticks - idle_ticks)) / total_ticks;
/* 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 (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;
}
/* Check for frequency increase */
if (load > dbs_tuners_ins.up_threshold) {
/* if we are already at full speed then break out early */
if (policy->cur == policy->max)
return;
@ -323,50 +294,22 @@ static void dbs_check_cpu(int cpu)
}
/* Check for frequency decrease */
down_skip[cpu]++;
if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor)
return;
idle_ticks = UINT_MAX;
for_each_cpu_mask(j, policy->cpus) {
unsigned int tmp_idle_ticks, total_idle_ticks;
struct cpu_dbs_info_s *j_dbs_info;
j_dbs_info = &per_cpu(cpu_dbs_info, j);
/* 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;
if (tmp_idle_ticks < idle_ticks)
idle_ticks = tmp_idle_ticks;
}
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;
total_ticks = usecs_to_jiffies(freq_down_sampling_rate);
/*
* 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) /
if (load < (dbs_tuners_ins.up_threshold - 10)) {
unsigned int freq_next;
freq_next = (policy->cur * load) /
(dbs_tuners_ins.up_threshold - 10);
if (freq_next < policy->min)
freq_next = policy->min;
if (freq_next <= ((policy->cur * 95) / 100))
__cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_L);
}
}
static void do_dbs_timer(void *data)
@ -432,9 +375,8 @@ 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(j);
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 = get_jiffies_64();
}
this_dbs_info->enable = 1;
sysfs_create_group(&policy->kobj, &dbs_attr_group);

2
include/asm-generic/cputime.h
View file

@ -24,7 +24,9 @@ typedef u64 cputime64_t;
#define cputime64_zero (0ULL)
#define cputime64_add(__a, __b) ((__a) + (__b))
#define cputime64_sub(__a, __b) ((__a) - (__b))
#define cputime64_to_jiffies64(__ct) (__ct)
#define jiffies64_to_cputime64(__jif) (__jif)
#define cputime_to_cputime64(__ct) ((u64) __ct)