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Date: Sat, 30 Mar 2013 00:27:34 +0200
From: Stratos Karafotis <stratosk@...aphore.gr>
To: "Rafael J. Wysocki" <rjw@...k.pl>
CC: Viresh Kumar <viresh.kumar@...aro.org>, cpufreq@...r.kernel.org,
linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 linux-next] cpufreq: ondemand: Calculate gradient of
CPU load to early increase frequency
On 02/22/2013 03:56 AM, Viresh Kumar wrote:
> On 21 February 2013 23:09, Stratos Karafotis <stratosk@...aphore.gr> wrote:
>
>> Signed-off-by: Stratos Karafotis <stratosk@...aphore.gr>
>
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
>
Hi Rafael,
In case you are interested in this patch I rebased it to the latest linux-pm/bleeding-edge.
Thanks,
Stratos
------------------------------------------
Instead of checking only the absolute value of CPU load_freq to increase
frequency, we detect forthcoming CPU load rise and increase frequency
earlier.
Every sampling rate, we calculate the gradient of load_freq. If it is
too steep we assume that the load most probably will go over
up_threshold in next iteration(s) and we increase frequency immediately.
New tuners are introduced:
- early_demand: to enable this functionality (disabled by default).
- grad_up_threshold: over this gradient of load we will increase
frequency immediately.
Signed-off-by: Stratos Karafotis <stratosk@...aphore.gr>
---
drivers/cpufreq/cpufreq_governor.c | 1 +
drivers/cpufreq/cpufreq_governor.h | 3 ++
drivers/cpufreq/cpufreq_ondemand.c | 59 +++++++++++++++++++++++++++++++++++++-
3 files changed, 62 insertions(+), 1 deletion(-)
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index 41e5e56..1d9abc4 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -328,6 +328,7 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
} else {
od_dbs_info->rate_mult = 1;
od_dbs_info->sample_type = OD_NORMAL_SAMPLE;
+ od_dbs_info->prev_load_freq = 0;
od_ops->powersave_bias_init_cpu(cpu);
}
diff --git a/drivers/cpufreq/cpufreq_governor.h b/drivers/cpufreq/cpufreq_governor.h
index 1f7de13..c33b37a 100644
--- a/drivers/cpufreq/cpufreq_governor.h
+++ b/drivers/cpufreq/cpufreq_governor.h
@@ -95,6 +95,7 @@ struct od_cpu_dbs_info_s {
unsigned int freq_hi_jiffies;
unsigned int rate_mult;
unsigned int sample_type:1;
+ unsigned int prev_load_freq;
};
struct cs_cpu_dbs_info_s {
@@ -113,6 +114,8 @@ struct od_dbs_tuners {
unsigned int adj_up_threshold;
unsigned int powersave_bias;
unsigned int io_is_busy;
+ unsigned int grad_up_threshold;
+ unsigned int early_demand;
};
struct cs_dbs_tuners {
diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index 29ed48a..6cd59a7 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -31,6 +31,7 @@
#define DEF_FREQUENCY_DOWN_DIFFERENTIAL (10)
#define DEF_FREQUENCY_UP_THRESHOLD (80)
#define DEF_SAMPLING_DOWN_FACTOR (1)
+#define DEF_GRAD_UP_THRESHOLD (50)
#define MAX_SAMPLING_DOWN_FACTOR (100000)
#define MICRO_FREQUENCY_DOWN_DIFFERENTIAL (3)
#define MICRO_FREQUENCY_UP_THRESHOLD (95)
@@ -168,11 +169,26 @@ static void od_check_cpu(int cpu, unsigned int load_freq)
struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;
struct dbs_data *dbs_data = policy->governor_data;
struct od_dbs_tuners *od_tuners = dbs_data->tuners;
+ int boost_freq = 0;
dbs_info->freq_lo = 0;
+ /*
+ * Calculate the gradient of load_freq. If it is too steep we assume
+ * that the load will go over up_threshold in next iteration(s) and
+ * we increase the frequency immediately
+ */
+ if (od_tuners->early_demand) {
+ if (load_freq > dbs_info->prev_load_freq &&
+ (load_freq - dbs_info->prev_load_freq >
+ od_tuners->grad_up_threshold * policy->cur))
+ boost_freq = 1;
+
+ dbs_info->prev_load_freq = load_freq;
+ }
+
/* Check for frequency increase */
- if (load_freq > od_tuners->up_threshold * policy->cur) {
+ if (boost_freq || load_freq > od_tuners->up_threshold * policy->cur) {
/* If switching to max speed, apply sampling_down_factor */
if (policy->cur < policy->max)
dbs_info->rate_mult =
@@ -454,12 +470,47 @@ static ssize_t store_powersave_bias(struct cpufreq_policy *policy,
return count;
}
+static ssize_t store_grad_up_threshold(struct cpufreq_policy *policy,
+ const char *buf, size_t count)
+{
+ struct dbs_data *dbs_data = policy->governor_data;
+ struct od_dbs_tuners *od_tuners = dbs_data->tuners;
+ unsigned int input;
+ int ret;
+ ret = sscanf(buf, "%u", &input);
+
+ if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
+ input < MIN_FREQUENCY_UP_THRESHOLD) {
+ return -EINVAL;
+ }
+
+ od_tuners->grad_up_threshold = input;
+ return count;
+}
+
+static ssize_t store_early_demand(struct cpufreq_policy *policy,
+ const char *buf, size_t count)
+{
+ struct dbs_data *dbs_data = policy->governor_data;
+ struct od_dbs_tuners *od_tuners = dbs_data->tuners;
+ unsigned int input;
+ int ret;
+
+ ret = sscanf(buf, "%u", &input);
+ if (ret != 1)
+ return -EINVAL;
+ od_tuners->early_demand = !!input;
+ return count;
+}
+
show_one(od, sampling_rate, sampling_rate);
show_one(od, io_is_busy, io_is_busy);
show_one(od, up_threshold, up_threshold);
show_one(od, sampling_down_factor, sampling_down_factor);
show_one(od, ignore_nice, ignore_nice);
show_one(od, powersave_bias, powersave_bias);
+show_one(od, grad_up_threshold, grad_up_threshold);
+show_one(od, early_demand, early_demand);
declare_show_sampling_rate_min();
cpufreq_freq_attr_rw(sampling_rate);
@@ -468,6 +519,8 @@ cpufreq_freq_attr_rw(up_threshold);
cpufreq_freq_attr_rw(sampling_down_factor);
cpufreq_freq_attr_rw(ignore_nice);
cpufreq_freq_attr_rw(powersave_bias);
+cpufreq_freq_attr_rw(grad_up_threshold);
+cpufreq_freq_attr_rw(early_demand);
cpufreq_freq_attr_ro(sampling_rate_min);
static struct attribute *dbs_attributes[] = {
@@ -478,6 +531,8 @@ static struct attribute *dbs_attributes[] = {
&ignore_nice.attr,
&powersave_bias.attr,
&io_is_busy.attr,
+ &grad_up_threshold.attr,
+ &early_demand.attr,
NULL
};
@@ -525,9 +580,11 @@ static int od_init(struct dbs_data *dbs_data)
}
tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
+ tuners->grad_up_threshold = DEF_GRAD_UP_THRESHOLD;
tuners->ignore_nice = 0;
tuners->powersave_bias = 0;
tuners->io_is_busy = should_io_be_busy();
+ tuners->early_demand = 0;
dbs_data->tuners = tuners;
mutex_init(&dbs_data->mutex);
--
1.8.1.4
--
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