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Subject[PATCH 2/5] cpufreq: star/stop cpufreq timers on cpu hotplug
Date
Add a CPU notifier to start and stop individual core timers on CPU
hotplug events when running on CPUs with SW coordinated frequency.

Signed-off-by: Fabio Baltieri <fabio.baltieri@linaro.org>
---
drivers/cpufreq/cpufreq_governor.c | 51 ++++++++++++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)

diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index b0e4506..e881250 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -25,9 +25,12 @@
#include <linux/tick.h>
#include <linux/types.h>
#include <linux/workqueue.h>
+#include <linux/cpu.h>

#include "cpufreq_governor.h"

+static DEFINE_PER_CPU(struct dbs_data *, cpu_cur_dbs);
+
static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall)
{
u64 idle_time;
@@ -185,6 +188,46 @@ static inline void dbs_timer_exit(struct cpu_dbs_common_info *cdbs)
cancel_delayed_work_sync(&cdbs->work);
}

+static int __cpuinit cpu_callback(struct notifier_block *nfb,
+ unsigned long action, void *hcpu)
+{
+ unsigned int cpu = (unsigned long)hcpu;
+ struct device *cpu_dev = get_cpu_device(cpu);
+ struct dbs_data *dbs_data = per_cpu(cpu_cur_dbs, cpu);
+ struct cpu_dbs_common_info *cpu_cdbs = dbs_data->get_cpu_cdbs(cpu);
+ unsigned int sampling_rate;
+
+ if (dbs_data->governor == GOV_CONSERVATIVE) {
+ struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
+ sampling_rate = cs_tuners->sampling_rate;
+ } else {
+ struct od_dbs_tuners *od_tuners = dbs_data->tuners;
+ sampling_rate = od_tuners->sampling_rate;
+ }
+
+ if (cpu_dev) {
+ switch (action) {
+ case CPU_ONLINE:
+ case CPU_ONLINE_FROZEN:
+ case CPU_DOWN_FAILED:
+ case CPU_DOWN_FAILED_FROZEN:
+ dbs_timer_init(dbs_data, cpu_cdbs,
+ sampling_rate, cpu);
+ break;
+ case CPU_DOWN_PREPARE:
+ case CPU_DOWN_PREPARE_FROZEN:
+ dbs_timer_exit(cpu_cdbs);
+ break;
+ }
+ }
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block __refdata ondemand_cpu_notifier = {
+ .notifier_call = cpu_callback,
+};
+
int cpufreq_governor_dbs(struct dbs_data *dbs_data,
struct cpufreq_policy *policy, unsigned int event)
{
@@ -296,7 +339,11 @@ second_time:
j_cdbs = dbs_data->get_cpu_cdbs(j);
dbs_timer_init(dbs_data, j_cdbs,
*sampling_rate, j);
+
+ per_cpu(cpu_cur_dbs, j) = dbs_data;
}
+
+ register_hotcpu_notifier(&ondemand_cpu_notifier);
} else {
dbs_timer_init(dbs_data, cpu_cdbs, *sampling_rate, cpu);
}
@@ -307,11 +354,15 @@ second_time:
cs_dbs_info->enable = 0;

if (dbs_sw_coordinated_cpus(cpu_cdbs)) {
+ unregister_hotcpu_notifier(&ondemand_cpu_notifier);
+
for_each_cpu(j, policy->cpus) {
struct cpu_dbs_common_info *j_cdbs;

j_cdbs = dbs_data->get_cpu_cdbs(j);
dbs_timer_exit(j_cdbs);
+
+ per_cpu(cpu_cur_dbs, j) = NULL;
}
} else {
dbs_timer_exit(cpu_cdbs);
--
1.7.12.1


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