Adds best_wake_cpu() to the power driver interface allowing the power
driver to influence which cpu will be woken up when additional cpus
are needed. Currently only a place holder until idle interface is in
place.
Signed-off-by: Morten Rasmussen <morten.rasmus...@arm.com>
---
drivers/cpufreq/cpufreq_schedpower.c | 11 +++++++++++
include/linux/sched/power.h | 2 ++
kernel/sched/fair.c | 5 ++++-
kernel/sched/power.c | 9 +++++++++
kernel/sched/sched.h | 6 ++++++
5 files changed, 32 insertions(+), 1 deletion(-)
diff --git a/drivers/cpufreq/cpufreq_schedpower.c
b/drivers/cpufreq/cpufreq_schedpower.c
index 5952c79..62847ca 100644
--- a/drivers/cpufreq/cpufreq_schedpower.c
+++ b/drivers/cpufreq/cpufreq_schedpower.c
@@ -187,6 +187,16 @@ int pdriver_go_slower(int cpu, int hint)
return 1;
}
+int pdriver_best_wake_cpu(void)
+{
+ /*
+ * Place holder. Should ideally determine the best cpu to wake up
+ * when more cpus are needed. This may be based on coupled C-states,
+ * power domains, and other platform specific factors.
+ */
+ return nr_cpu_ids;
+}
+
void pdriver_late_callback(int cpu)
{
struct cpufreq_schedpower_cpuinfo *pcpu_info;
@@ -202,6 +212,7 @@ static struct power_driver pdriver = {
.at_max_capacity = pdriver_at_max_capacity,
.go_faster = pdriver_go_faster,
.go_slower = pdriver_go_slower,
+ .best_wake_cpu = pdriver_best_wake_cpu,
.late_callback = pdriver_late_callback,
};
diff --git a/include/linux/sched/power.h b/include/linux/sched/power.h
index aba5f47..5d76f44 100644
--- a/include/linux/sched/power.h
+++ b/include/linux/sched/power.h
@@ -25,6 +25,8 @@ struct power_driver {
int (*go_faster) (int cpu, int hint);
/* Decrease cpu capacity hint */
int (*go_slower) (int cpu, int hint);
+ /* Best cpu to wake up */
+ int (*best_wake_cpu) (void);
/* Scheduler call-back without rq lock held and with irq enabled */
void (*late_callback) (int cpu);
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ee87e65..d32fb97 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5458,7 +5458,10 @@ static struct {
static inline int find_new_ilb(int call_cpu)
{
- int ilb = cpumask_first(nohz.idle_cpus_mask);
+ int ilb = best_wake_cpu();
+
+ if (ilb >= nr_cpu_ids)
+ ilb = cpumask_first(nohz.idle_cpus_mask);
if (ilb < nr_cpu_ids && idle_cpu(ilb))
return ilb;
diff --git a/kernel/sched/power.c b/kernel/sched/power.c
index f70b563..e1357d2 100644
--- a/kernel/sched/power.c
+++ b/kernel/sched/power.c
@@ -11,6 +11,7 @@
*/
#include <linux/kernel.h>
+#include <linux/cpumask.h>
#include <linux/sched/power.h>
static struct power_driver *power_driver;
@@ -56,6 +57,14 @@ int go_slower(int cpu, int hint)
return power_driver->go_slower(cpu, hint);
}
+int best_wake_cpu(void)
+{
+ if (!power_driver)
+ return nr_cpu_ids;
+
+ return power_driver->best_wake_cpu();
+}
+
void power_late_callback(int cpu)
{
if (!power_driver)
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 88e7968..a368734 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1370,6 +1370,7 @@ extern void power_late_callback(int cpu);
extern int at_max_capacity(int cpu);
extern int go_faster(int cpu, int hint);
extern int go_slower(int cpu, int hint);
+extern int best_wake_cpu(void);
#else
static inline void power_late_callback(int cpu)
{
@@ -1389,4 +1390,9 @@ static inline int go_slower(int cpu, int hint)
{
return 0;
}
+
+static inline int best_wake_cpu(void)
+{
+ return nr_cpu_ids;
+}
#endif /* CONFIG_SCHED_POWER */
--
1.7.9.5
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