[PATCH V4 6/6] cpufreq: Add QoS requests for userspace constraints

From: Viresh Kumar
Date: Thu Jun 20 2019 - 03:41:17 EST


This implements QoS requests to manage userspace configuration of min
and max frequency.

Reviewed-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
drivers/cpufreq/cpufreq.c | 87 ++++++++++++++++++++-------------------
include/linux/cpufreq.h | 8 +---
2 files changed, 46 insertions(+), 49 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index b47a6c094171..5d050b4a3806 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -718,23 +718,15 @@ static ssize_t show_scaling_cur_freq(struct cpufreq_policy *policy, char *buf)
static ssize_t store_##file_name \
(struct cpufreq_policy *policy, const char *buf, size_t count) \
{ \
- int ret, temp; \
- struct cpufreq_policy new_policy; \
+ unsigned long val; \
+ int ret; \
\
- memcpy(&new_policy, policy, sizeof(*policy)); \
- new_policy.min = policy->user_policy.min; \
- new_policy.max = policy->user_policy.max; \
- \
- ret = sscanf(buf, "%u", &new_policy.object); \
+ ret = sscanf(buf, "%lu", &val); \
if (ret != 1) \
return -EINVAL; \
\
- temp = new_policy.object; \
- ret = cpufreq_set_policy(policy, &new_policy); \
- if (!ret) \
- policy->user_policy.object = temp; \
- \
- return ret ? ret : count; \
+ ret = dev_pm_qos_update_request(policy->object##_freq_req, val);\
+ return ret >= 0 ? count : ret; \
}

store_one(scaling_min_freq, min);
@@ -1126,8 +1118,6 @@ static void reeval_frequency_limits(struct cpufreq_policy *policy)
new_policy = *policy;
pr_debug("updating policy for CPU %u\n", policy->cpu);

- new_policy.min = policy->user_policy.min;
- new_policy.max = policy->user_policy.max;
cpufreq_set_policy(policy, &new_policy);
}

@@ -1237,6 +1227,12 @@ static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu)
goto err_min_qos_notifier;
}

+ policy->min_freq_req = kzalloc(2 * sizeof(*policy->min_freq_req),
+ GFP_KERNEL);
+ if (!policy->min_freq_req)
+ goto err_max_qos_notifier;
+
+ policy->max_freq_req = policy->min_freq_req + 1;
INIT_LIST_HEAD(&policy->policy_list);
init_rwsem(&policy->rwsem);
spin_lock_init(&policy->transition_lock);
@@ -1247,6 +1243,9 @@ static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu)
policy->cpu = cpu;
return policy;

+err_max_qos_notifier:
+ dev_pm_qos_remove_notifier(dev, &policy->nb_max,
+ DEV_PM_QOS_MAX_FREQUENCY);
err_min_qos_notifier:
dev_pm_qos_remove_notifier(dev, &policy->nb_min,
DEV_PM_QOS_MIN_FREQUENCY);
@@ -1282,6 +1281,9 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy)
DEV_PM_QOS_MAX_FREQUENCY);
dev_pm_qos_remove_notifier(dev, &policy->nb_min,
DEV_PM_QOS_MIN_FREQUENCY);
+ dev_pm_qos_remove_request(policy->max_freq_req);
+ dev_pm_qos_remove_request(policy->min_freq_req);
+ kfree(policy->min_freq_req);

cpufreq_policy_put_kobj(policy);
free_cpumask_var(policy->real_cpus);
@@ -1360,16 +1362,30 @@ static int cpufreq_online(unsigned int cpu)
cpumask_and(policy->cpus, policy->cpus, cpu_online_mask);

if (new_policy) {
- policy->user_policy.min = policy->min;
- policy->user_policy.max = policy->max;
+ struct device *dev = get_cpu_device(cpu);

for_each_cpu(j, policy->related_cpus) {
per_cpu(cpufreq_cpu_data, j) = policy;
add_cpu_dev_symlink(policy, j);
}
- } else {
- policy->min = policy->user_policy.min;
- policy->max = policy->user_policy.max;
+
+ ret = dev_pm_qos_add_request(dev, policy->min_freq_req,
+ DEV_PM_QOS_MIN_FREQUENCY,
+ policy->min);
+ if (ret < 0) {
+ dev_err(dev, "Failed to add min-freq constraint (%d)\n",
+ ret);
+ goto out_destroy_policy;
+ }
+
+ ret = dev_pm_qos_add_request(dev, policy->max_freq_req,
+ DEV_PM_QOS_MAX_FREQUENCY,
+ policy->max);
+ if (ret < 0) {
+ dev_err(dev, "Failed to add max-freq constraint (%d)\n",
+ ret);
+ goto out_destroy_policy;
+ }
}

if (cpufreq_driver->get && has_target()) {
@@ -2345,7 +2361,6 @@ int cpufreq_set_policy(struct cpufreq_policy *policy,
{
struct cpufreq_governor *old_gov;
struct device *cpu_dev = get_cpu_device(policy->cpu);
- unsigned long min, max;
int ret;

pr_debug("setting new policy for CPU %u: %u - %u kHz\n",
@@ -2353,24 +2368,12 @@ int cpufreq_set_policy(struct cpufreq_policy *policy,

memcpy(&new_policy->cpuinfo, &policy->cpuinfo, sizeof(policy->cpuinfo));

- /*
- * This check works well when we store new min/max freq attributes,
- * because new_policy is a copy of policy with one field updated.
- */
- if (new_policy->min > new_policy->max)
- return -EINVAL;
-
/*
* PM QoS framework collects all the requests from users and provide us
* the final aggregated value here.
*/
- min = dev_pm_qos_read_value(cpu_dev, DEV_PM_QOS_MIN_FREQUENCY);
- max = dev_pm_qos_read_value(cpu_dev, DEV_PM_QOS_MAX_FREQUENCY);
-
- if (min > new_policy->min)
- new_policy->min = min;
- if (max < new_policy->max)
- new_policy->max = max;
+ new_policy->min = dev_pm_qos_read_value(cpu_dev, DEV_PM_QOS_MIN_FREQUENCY);
+ new_policy->max = dev_pm_qos_read_value(cpu_dev, DEV_PM_QOS_MAX_FREQUENCY);

/* verify the cpu speed can be set within this limit */
ret = cpufreq_driver->verify(new_policy);
@@ -2459,10 +2462,9 @@ int cpufreq_set_policy(struct cpufreq_policy *policy,
* @cpu: CPU to re-evaluate the policy for.
*
* Update the current frequency for the cpufreq policy of @cpu and use
- * cpufreq_set_policy() to re-apply the min and max limits saved in the
- * user_policy sub-structure of that policy, which triggers the evaluation
- * of policy notifiers and the cpufreq driver's ->verify() callback for the
- * policy in question, among other things.
+ * cpufreq_set_policy() to re-apply the min and max limits, which triggers the
+ * evaluation of policy notifiers and the cpufreq driver's ->verify() callback
+ * for the policy in question, among other things.
*/
void cpufreq_update_policy(unsigned int cpu)
{
@@ -2522,10 +2524,9 @@ static int cpufreq_boost_set_sw(int state)
break;
}

- down_write(&policy->rwsem);
- policy->user_policy.max = policy->max;
- cpufreq_governor_limits(policy);
- up_write(&policy->rwsem);
+ ret = dev_pm_qos_update_request(policy->max_freq_req, policy->max);
+ if (ret)
+ break;
}

return ret;
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index d8622cf3f46c..b6245f512a26 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -50,11 +50,6 @@ struct cpufreq_cpuinfo {
unsigned int transition_latency;
};

-struct cpufreq_user_policy {
- unsigned int min; /* in kHz */
- unsigned int max; /* in kHz */
-};
-
struct cpufreq_policy {
/* CPUs sharing clock, require sw coordination */
cpumask_var_t cpus; /* Online CPUs only */
@@ -84,7 +79,8 @@ struct cpufreq_policy {
struct work_struct update; /* if update_policy() needs to be
* called, but you're in IRQ context */

- struct cpufreq_user_policy user_policy;
+ struct dev_pm_qos_request *min_freq_req;
+ struct dev_pm_qos_request *max_freq_req;
struct cpufreq_frequency_table *freq_table;
enum cpufreq_table_sorting freq_table_sorted;

--
2.21.0.rc0.269.g1a574e7a288b