[RFCv5 PATCH 29/46] sched: Determine the current sched_group idle-state

Morten Rasmussen
2015-07-07T18:59:09Z

From: Dietmar Eggemann <dietmar.eggemann@arm.com>

To estimate the energy consumption of a sched_group in
sched_group_energy() it is necessary to know which idle-state the group
is in when it is idle. For now, it is assumed that this is the current
idle-state (though it might be wrong). Based on the individual cpu
idle-states group_idle_state() finds the group idle-state.

cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>

Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
---
kernel/sched/fair.c | 27 +++++++++++++++++++++++----
1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 99e43ee..a134028 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4966,6 +4966,22 @@ static bool cpu_overutilized(int cpu)
(get_cpu_usage(cpu) * capacity_margin);
}

+static int group_idle_state(struct sched_group *sg)
+{
+ int i, state = INT_MAX;
+
+ /* Find the shallowest idle state in the sched group. */
+ for_each_cpu(i, sched_group_cpus(sg))
+ state = min(state, idle_get_state_idx(cpu_rq(i)));
+
+ /* Transform system into sched domain idle state. */
+ if (sg->sge->nr_idle_states_below > 1)
+ state -= sg->sge->nr_idle_states_below - 1;
+
+ /* Clamp state to the range of sched domain idle states. */
+ return clamp_t(int, state, 0, sg->sge->nr_idle_states - 1);
+}
+
/*
* sched_group_energy(): Returns absolute energy consumption of cpus belonging
* to the sched_group including shared resources shared only by members of the
@@ -5008,7 +5024,8 @@ static unsigned int sched_group_energy(struct energy_env *eenv)

do {
unsigned long group_util;
- int sg_busy_energy, sg_idle_energy, cap_idx;
+ int sg_busy_energy, sg_idle_energy;
+ int cap_idx, idle_idx;

if (sg_shared_cap && sg_shared_cap->group_weight >= sg->group_weight)
eenv->sg_cap = sg_shared_cap;
@@ -5016,11 +5033,13 @@ static unsigned int sched_group_energy(struct energy_env *eenv)
eenv->sg_cap = sg;

cap_idx = find_new_capacity(eenv, sg->sge);
+ idle_idx = group_idle_state(sg);
group_util = group_norm_usage(eenv, sg);
sg_busy_energy = (group_util * sg->sge->cap_states[cap_idx].power)
- >> SCHED_CAPACITY_SHIFT;
- sg_idle_energy = ((SCHED_LOAD_SCALE-group_util) * sg->sge->idle_states[0].power)
- >> SCHED_CAPACITY_SHIFT;
+ >> SCHED_CAPACITY_SHIFT;
+ sg_idle_energy = ((SCHED_LOAD_SCALE-group_util)
+ * sg->sge->idle_states[idle_idx].power)
+ >> SCHED_CAPACITY_SHIFT;

total_energy += sg_busy_energy + sg_idle_energy;

--
1.9.1