Extends the power scheduler capacity management algorithm to handle
frequency scaling and provide basic frequency/P-state selection hints
to the power driver.
Signed-off-by: Morten Rasmussen <morten.rasmus...@arm.com>
CC: Ingo Molnar <mi...@kernel.org>
CC: Peter Zijlstra <pet...@infradead.org>
CC: Catalin Marinas <catalin.mari...@arm.com>
---
kernel/sched/power.c | 33 ++++++++++++++++++++++++++++-----
1 file changed, 28 insertions(+), 5 deletions(-)
diff --git a/kernel/sched/power.c b/kernel/sched/power.c
index 9e44c0e..5fc32b0 100644
--- a/kernel/sched/power.c
+++ b/kernel/sched/power.c
@@ -21,6 +21,8 @@
#define INTERVAL 5 /* ms */
#define CPU_FULL 90 /* Busy %-age - TODO: Make tunable */
+#define CPU_TARGET 80 /* Target busy %-age - TODO: Make tunable */
+#define CPU_EMPTY 5 /* Idle noise %-age - TODO: Make tunable */
struct power_domain {
/* Domain hierarchy pointers */
@@ -87,7 +89,7 @@ static void update_cpu_load(void)
u32 sum = rq->avg.runnable_avg_sum;
u32 period = rq->avg.runnable_avg_period;
- load = (sum * power_sched_cpu_power(i)) / (period+1);
+ load = (sum * cpu_pd(i)->curr_power) / (period+1);
cpu_pd(i)->load = load;
cpu_pd(i)->nr_tasks = rq->nr_running;
@@ -160,19 +162,40 @@ static void calculate_cpu_capacities(void)
for_each_online_cpu(i) {
int t_cap = 0;
- int sched_power = cpu_pd(i)->sched_power;
+ int curr_power = cpu_pd(i)->curr_power;
stats = cpu_pd(i);
- t_cap = sched_power - stats->load;
+ t_cap = curr_power - stats->load;
- if (t_cap < (sched_power * (100-CPU_FULL)) / 100) {
+ if (t_cap < (curr_power * (100-CPU_FULL)) / 100) {
/* Potential for spreading load */
if (stats->nr_tasks > 1)
t_cap = -(stats->load / stats->nr_tasks);
+ /*
+ * Single task and higher p-state available on
+ * current cpu
+ */
+ else if (power_driver &&
+ curr_power < cpu_pd(i)->arch_power)
+ power_driver->req_power(i,
+ cpu_pd(i)->arch_power);
+ } else {
+ /* cpu not full - request lower p-state */
+ /*
+ * TODO global view of spare capacity is needed to do
+ * proper p-state selection
+ */
+ if (power_driver)
+ power_driver->req_power(i,
+ (stats->load*100)/CPU_TARGET);
+
+ /* Don't let noise keep the cpu awake */
+ if (t_cap > (curr_power * CPU_EMPTY) / 100)
+ t_cap = curr_power;
}
/* Do we have enough capacity already? */
- if (spare_cap + t_cap > sched_power) {
+ if (spare_cap + t_cap > curr_power) {
cpu_pd(i)->sched_power = 1;
} else {
cpu_pd(i)->sched_power = cpu_pd(i)->arch_power;
--
1.7.9.5
--
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