[PATCH v4 5/7] cpufreq: Calculate number of busy CPUs

[Lukasz Majewski]

In the core governor code, per cpu load value is calculated. This patch
uses it to mark processor as a "busy" one, when load value is higher than
90%.

New cpufreq sysfs attribute is created (busy_cpus). It is read only
and provides information about number of actually busy CPU.

Signed-off-by: Lukasz Majewski <l.majewski@xxxxxxxxxxx>
Signed-off-by: Myungjoo Ham <myungjoo.ham@xxxxxxxxxxx>

Changes for v4:
- New patch
---
 drivers/cpufreq/cpufreq.c          |   31 ++++++++++++++++++++++++++++++-
 drivers/cpufreq/cpufreq_governor.c |    1 +
 include/linux/cpufreq.h            |    3 +++
 3 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 9141d33..f785273 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -48,6 +48,7 @@ static DEFINE_PER_CPU(char[CPUFREQ_NAME_LEN], cpufreq_cpu_governor);
 #endif
 static DEFINE_RWLOCK(cpufreq_driver_lock);
 static LIST_HEAD(cpufreq_policy_list);
+static cpumask_t cpufreq_busy_cpus;
 
 /*
  * cpu_policy_rwsem is a per CPU reader-writer semaphore designed to cure
@@ -317,6 +318,13 @@ EXPORT_SYMBOL_GPL(cpufreq_notify_transition);
 /*********************************************************************
  *                          SYSFS INTERFACE                          *
  *********************************************************************/
+ssize_t show_busy_cpus(struct kobject *kobj,
+				 struct attribute *attr, char *buf)
+{
+	return sprintf(buf, "%d\n", cpufreq_num_busy_cpu());
+}
+define_one_global_ro(busy_cpus);
+
 ssize_t show_boost(struct kobject *kobj,
 				 struct attribute *attr, char *buf)
 {
@@ -1980,6 +1988,17 @@ int cpufreq_boost_enabled(void)
 	return boost_enabled;
 }
 
+int cpufreq_num_busy_cpu(void)
+{
+	return cpumask_weight(&cpufreq_busy_cpus);
+}
+
+void cpufreq_set_busy_cpu(int cpu, int val)
+{
+	val ? cpumask_set_cpu(cpu, &cpufreq_busy_cpus) :
+		cpumask_clear_cpu(cpu, &cpufreq_busy_cpus);
+}
+
 /*********************************************************************
  *               REGISTER / UNREGISTER CPUFREQ DRIVER                *
  *********************************************************************/
@@ -2019,6 +2038,13 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 	cpufreq_driver = driver_data;
 	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
 
+	ret = cpufreq_sysfs_create_file(&(busy_cpus.attr));
+	if (ret) {
+		pr_err("%s: cannot register global busy_cpus sysfs file\n",
+		       __func__);
+		goto err_null_driver;
+	}
+
 	if (!cpufreq_driver->boost_supported)
 		boost.attr.mode = 0444;
 
@@ -2026,7 +2052,7 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 	if (ret) {
 		pr_err("%s: cannot register global boost sysfs file\n",
 		       __func__);
-		goto err_null_driver;
+		goto err_busy_idle_unreg;
 	}
 
 	ret = subsys_interface_register(&cpufreq_interface);
@@ -2058,6 +2084,8 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 	return 0;
 err_if_unreg:
 	subsys_interface_unregister(&cpufreq_interface);
+err_busy_idle_unreg:
+	cpufreq_sysfs_remove_file(&(busy_cpus.attr));
 err_null_driver:
 	write_lock_irqsave(&cpufreq_driver_lock, flags);
 	cpufreq_driver = NULL;
@@ -2086,6 +2114,7 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
 
 	subsys_interface_unregister(&cpufreq_interface);
 
+	cpufreq_sysfs_remove_file(&(busy_cpus.attr));
 	cpufreq_sysfs_remove_file(&(boost.attr));
 	unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
 
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index 077cea7..3402533 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -148,6 +148,7 @@ void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
 			continue;
 
 		load = 100 * (wall_time - idle_time) / wall_time;
+		cpufreq_set_busy_cpu(j, load > 90 ? 1 : 0);
 
 		if (dbs_data->cdata->governor == GOV_ONDEMAND) {
 			int freq_avg = __cpufreq_driver_getavg(policy, j);
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 4783c4c..536abfc 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -436,6 +436,9 @@ int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
 int cpufreq_boost_trigger_state(int state);
 int cpufreq_boost_supported(void);
 int cpufreq_boost_enabled(void);
+
+void cpufreq_set_busy_cpu(int cpu, int val);
+int cpufreq_num_busy_cpu(void);
 /* the following 3 funtions are for cpufreq core use only */
 struct cpufreq_frequency_table *cpufreq_frequency_get_table(unsigned int cpu);
 
-- 
1.7.10.4

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