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Message-ID: <2899343.d3UcWvo4TA@vostro.rjw.lan>
Date: Fri, 10 Jun 2016 03:00:37 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM list <linux-pm@...r.kernel.org>
Cc: Viresh Kumar <viresh.kumar@...aro.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: [PATCH] cpufreq: conservative: Do not use transition notifications
From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
The conservative governor registers a transition notifier so it
can update its internal requested_freq value if it falls out of the
policy->min...policy->max range, but that's not the most
straightforward way to achieve that.
To do it in a more straightforward way, first make sure that
cs_dbs_timer() will only set frequencies between min and max.
With that, note that requested_freq will always fall between min
and max unless either policy->min or policy->max changes and the
governor's ->limits() callback will be invoked then.
Using this observation, add a ->limits callback pointer to
struct dbs_governor, make cpufreq_dbs_governor_limits() invoke
that callback if present, implement that callback in the conservative
governor to update requested_freq if needed and drop the transition
notifier from it, which also makes it possible to drop the
struct cs_governor definition from there and simplify the code
accordingly.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
drivers/cpufreq/cpufreq_conservative.c | 85 +++++++--------------------------
drivers/cpufreq/cpufreq_governor.c | 4 +
drivers/cpufreq/cpufreq_governor.h | 1
3 files changed, 25 insertions(+), 65 deletions(-)
Index: linux-pm/drivers/cpufreq/cpufreq_conservative.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/cpufreq_conservative.c
+++ linux-pm/drivers/cpufreq/cpufreq_conservative.c
@@ -106,7 +106,8 @@ static unsigned int cs_dbs_timer(struct
goto out;
freq_target = get_freq_target(cs_tuners, policy);
- if (dbs_info->requested_freq > freq_target)
+ if (dbs_info->requested_freq > freq_target
+ && dbs_info->requested_freq - freq_target > policy->min)
dbs_info->requested_freq -= freq_target;
else
dbs_info->requested_freq = policy->min;
@@ -119,13 +120,6 @@ static unsigned int cs_dbs_timer(struct
return dbs_data->sampling_rate;
}
-static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
- void *data);
-
-static struct notifier_block cs_cpufreq_notifier_block = {
- .notifier_call = dbs_cpufreq_notifier,
-};
-
/************************** sysfs interface ************************/
static ssize_t store_sampling_down_factor(struct gov_attr_set *attr_set,
@@ -254,13 +248,6 @@ static struct attribute *cs_attributes[]
/************************** sysfs end ************************/
-struct cs_governor {
- struct dbs_governor dbs_gov;
- unsigned int usage_count;
-};
-
-static struct cs_governor cs_gov;
-
static struct policy_dbs_info *cs_alloc(void)
{
struct cs_policy_dbs_info *dbs_info;
@@ -294,25 +281,11 @@ static int cs_init(struct dbs_data *dbs_
dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
jiffies_to_usecs(10);
- /*
- * This function and cs_exit() are only called under gov_dbs_data_mutex
- * which is global, so the cs_gov.usage_count accesses are guaranteed
- * to be serialized.
- */
- if (!cs_gov.usage_count++)
- cpufreq_register_notifier(&cs_cpufreq_notifier_block,
- CPUFREQ_TRANSITION_NOTIFIER);
-
return 0;
}
static void cs_exit(struct dbs_data *dbs_data)
{
- /* Protected by gov_dbs_data_mutex - see the comment in cs_init(). */
- if (!--cs_gov.usage_count)
- cpufreq_unregister_notifier(&cs_cpufreq_notifier_block,
- CPUFREQ_TRANSITION_NOTIFIER);
-
kfree(dbs_data->tuners);
}
@@ -324,47 +297,29 @@ static void cs_start(struct cpufreq_poli
dbs_info->requested_freq = policy->cur;
}
-static struct cs_governor cs_gov = {
- .dbs_gov = {
- .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("conservative"),
- .kobj_type = { .default_attrs = cs_attributes },
- .gov_dbs_timer = cs_dbs_timer,
- .alloc = cs_alloc,
- .free = cs_free,
- .init = cs_init,
- .exit = cs_exit,
- .start = cs_start,
- },
-};
-
-#define CPU_FREQ_GOV_CONSERVATIVE (&cs_gov.dbs_gov.gov)
-
-static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
- void *data)
+static void cs_limits(struct cpufreq_policy *policy)
{
- struct cpufreq_freqs *freq = data;
- struct cpufreq_policy *policy = cpufreq_cpu_get_raw(freq->cpu);
- struct cs_policy_dbs_info *dbs_info;
-
- if (!policy)
- return 0;
-
- /* policy isn't governed by conservative governor */
- if (policy->governor != CPU_FREQ_GOV_CONSERVATIVE)
- return 0;
+ struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
- dbs_info = to_dbs_info(policy->governor_data);
- /*
- * we only care if our internally tracked freq moves outside the 'valid'
- * ranges of frequency available to us otherwise we do not change it
- */
if (dbs_info->requested_freq > policy->max
- || dbs_info->requested_freq < policy->min)
- dbs_info->requested_freq = freq->new;
-
- return 0;
+ || dbs_info->requested_freq < policy->min)
+ dbs_info->requested_freq = policy->cur;
}
+static struct dbs_governor cs_governor = {
+ .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("conservative"),
+ .kobj_type = { .default_attrs = cs_attributes },
+ .gov_dbs_timer = cs_dbs_timer,
+ .alloc = cs_alloc,
+ .free = cs_free,
+ .init = cs_init,
+ .exit = cs_exit,
+ .start = cs_start,
+ .limits = cs_limits,
+};
+
+#define CPU_FREQ_GOV_CONSERVATIVE (&cs_governor.gov)
+
static int __init cpufreq_gov_dbs_init(void)
{
return cpufreq_register_governor(CPU_FREQ_GOV_CONSERVATIVE);
Index: linux-pm/drivers/cpufreq/cpufreq_governor.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/cpufreq_governor.c
+++ linux-pm/drivers/cpufreq/cpufreq_governor.c
@@ -545,6 +545,7 @@ EXPORT_SYMBOL_GPL(cpufreq_dbs_governor_s
void cpufreq_dbs_governor_limits(struct cpufreq_policy *policy)
{
+ struct dbs_governor *gov = dbs_governor_of(policy);
struct policy_dbs_info *policy_dbs = policy->governor_data;
mutex_lock(&policy_dbs->timer_mutex);
@@ -554,6 +555,9 @@ void cpufreq_dbs_governor_limits(struct
else if (policy->min > policy->cur)
__cpufreq_driver_target(policy, policy->min, CPUFREQ_RELATION_L);
+ if (gov->limits)
+ gov->limits(policy);
+
gov_update_sample_delay(policy_dbs, 0);
mutex_unlock(&policy_dbs->timer_mutex);
Index: linux-pm/drivers/cpufreq/cpufreq_governor.h
===================================================================
--- linux-pm.orig/drivers/cpufreq/cpufreq_governor.h
+++ linux-pm/drivers/cpufreq/cpufreq_governor.h
@@ -141,6 +141,7 @@ struct dbs_governor {
int (*init)(struct dbs_data *dbs_data);
void (*exit)(struct dbs_data *dbs_data);
void (*start)(struct cpufreq_policy *policy);
+ void (*limits)(struct cpufreq_policy *policy);
};
static inline struct dbs_governor *dbs_governor_of(struct cpufreq_policy *policy)
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