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From 1e9ffadc70a89ede023b79139debe4f6a17c5c7f Mon Sep 17 00:00:00 2001
From: Morten Rasmussen <morten.rasmussen@arm.com>
Date: Thu, 18 Dec 2014 14:47:18 +0000
Subject: [PATCH 53/92] sched: Calculate energy consumption of sched_group
For energy-aware load-balancing decisions it is necessary to know the
energy consumption estimates of groups of cpus. This patch introduces a
basic function, sched_group_energy(), which estimates the energy
consumption of the cpus in the group and any resources shared by the
members of the group.
NOTE: The function has five levels of identation and breaks the 80
character limit. Refactoring is necessary.
cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
(cherry picked from commit 1e09b216da57376d8321459eda52699cef8f7e1a)
Signed-off-by: Gaku Inami <gaku.inami.xw@bp.renesas.com>
---
kernel/sched/core.c | 4 ++
kernel/sched/fair.c | 156 +++++++++++++++++++++++++++++++++++++++++++++++++++
kernel/sched/sched.h | 1 +
3 files changed, 161 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f2642d4..431c7e0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6002,6 +6002,7 @@ static void destroy_sched_domains(struct sched_domain *sd)
DEFINE_PER_CPU(struct sched_domain *, sd_numa);
DEFINE_PER_CPU(struct sched_domain *, sd_asym);
DEFINE_PER_CPU(struct sched_domain *, sd_ea);
+DEFINE_PER_CPU(struct sched_domain *, sd_scs);
static void update_top_cache_domain(int cpu)
{
@@ -6036,6 +6037,9 @@ static void update_top_cache_domain(int cpu)
break;
}
rcu_assign_pointer(per_cpu(sd_ea, cpu), ea_sd);
+
+ sd = highest_flag_domain(cpu, SD_SHARE_CAP_STATES);
+ rcu_assign_pointer(per_cpu(sd_scs, cpu), sd);
}
/*
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 0085d4f..1b8dca7 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5331,6 +5331,162 @@ static inline bool energy_aware(void)
}
/*
+ * cpu_norm_util() returns the cpu util relative to a specific capacity,
+ * i.e. it's busy ratio, in the range [0..SCHED_CAPACITY_SCALE] which is useful
+ * for energy calculations. Using the scale-invariant util returned by
+ * cpu_util() and approximating scale-invariant util by:
+ *
+ * util ~ (curr_freq/max_freq)*1024 * capacity_orig/1024 * running_time/time
+ *
+ * the normalized util can be found using the specific capacity.
+ *
+ * capacity = capacity_orig * curr_freq/max_freq
+ *
+ * norm_util = running_time/time ~ util/capacity
+ */
+static unsigned long cpu_norm_util(int cpu, unsigned long capacity)
+{
+ int util = cpu_util(cpu);
+
+ if (util >= capacity)
+ return SCHED_CAPACITY_SCALE;
+
+ return (util << SCHED_CAPACITY_SHIFT)/capacity;
+}
+
+static unsigned long group_max_util(struct sched_group *sg)
+{
+ int i;
+ unsigned long max_util = 0;
+
+ for_each_cpu(i, sched_group_cpus(sg))
+ max_util = max(max_util, cpu_util(i));
+
+ return max_util;
+}
+
+/*
+ * group_norm_util() returns the approximated group util relative to it's
+ * current capacity (busy ratio) in the range [0..SCHED_CAPACITY_SCALE] for use
+ * in energy calculations. Since task executions may or may not overlap in time
+ * in the group the true normalized util is between max(cpu_norm_util(i)) and
+ * sum(cpu_norm_util(i)) when iterating over all cpus in the group, i. The
+ * latter is used as the estimate as it leads to a more pessimistic energy
+ * estimate (more busy).
+ */
+static unsigned long group_norm_util(struct sched_group *sg, int cap_idx)
+{
+ int i;
+ unsigned long util_sum = 0;
+ unsigned long capacity = sg->sge->cap_states[cap_idx].cap;
+
+ for_each_cpu(i, sched_group_cpus(sg))
+ util_sum += cpu_norm_util(i, capacity);
+
+ if (util_sum > SCHED_CAPACITY_SCALE)
+ return SCHED_CAPACITY_SCALE;
+ return util_sum;
+}
+
+static int find_new_capacity(struct sched_group *sg,
+ const struct sched_group_energy const *sge)
+{
+ int idx;
+ unsigned long util = group_max_util(sg);
+
+ for (idx = 0; idx < sge->nr_cap_states; idx++) {
+ if (sge->cap_states[idx].cap >= util)
+ return idx;
+ }
+
+ return idx;
+}
+
+/*
+ * sched_group_energy(): Computes the absolute energy consumption of cpus
+ * belonging to the sched_group including shared resources shared only by
+ * members of the group. Iterates over all cpus in the hierarchy below the
+ * sched_group starting from the bottom working it's way up before going to
+ * the next cpu until all cpus are covered at all levels. The current
+ * implementation is likely to gather the same util statistics multiple times.
+ * This can probably be done in a faster but more complex way.
+ * Note: sched_group_energy() may fail when racing with sched_domain updates.
+ */
+static int sched_group_energy(struct sched_group *sg_top)
+{
+ struct sched_domain *sd;
+ int cpu, total_energy = 0;
+ struct cpumask visit_cpus;
+ struct sched_group *sg;
+
+ WARN_ON(!sg_top->sge);
+
+ cpumask_copy(&visit_cpus, sched_group_cpus(sg_top));
+
+ while (!cpumask_empty(&visit_cpus)) {
+ struct sched_group *sg_shared_cap = NULL;
+
+ cpu = cpumask_first(&visit_cpus);
+
+ /*
+ * Is the group utilization affected by cpus outside this
+ * sched_group?
+ */
+ sd = rcu_dereference(per_cpu(sd_scs, cpu));
+
+ if (!sd)
+ /*
+ * We most probably raced with hotplug; returning a
+ * wrong energy estimation is better than entering an
+ * infinite loop.
+ */
+ return -EINVAL;
+
+ if (sd->parent)
+ sg_shared_cap = sd->parent->groups;
+
+ for_each_domain(cpu, sd) {
+ sg = sd->groups;
+
+ /* Has this sched_domain already been visited? */
+ if (sd->child && group_first_cpu(sg) != cpu)
+ break;
+
+ do {
+ struct sched_group *sg_cap_util;
+ unsigned long group_util;
+ int sg_busy_energy, sg_idle_energy, cap_idx;
+
+ if (sg_shared_cap && sg_shared_cap->group_weight >= sg->group_weight)
+ sg_cap_util = sg_shared_cap;
+ else
+ sg_cap_util = sg;
+
+ cap_idx = find_new_capacity(sg_cap_util, sg->sge);
+ group_util = group_norm_util(sg, cap_idx);
+ sg_busy_energy = (group_util * sg->sge->cap_states[cap_idx].power)
+ >> SCHED_CAPACITY_SHIFT;
+ sg_idle_energy = ((SCHED_CAPACITY_SCALE-group_util) * sg->sge->idle_states[0].power)
+ >> SCHED_CAPACITY_SHIFT;
+
+ total_energy += sg_busy_energy + sg_idle_energy;
+
+ if (!sd->child)
+ cpumask_xor(&visit_cpus, &visit_cpus, sched_group_cpus(sg));
+
+ if (cpumask_equal(sched_group_cpus(sg), sched_group_cpus(sg_top)))
+ goto next_cpu;
+
+ } while (sg = sg->next, sg != sd->groups);
+ }
+next_cpu:
+ continue;
+ }
+
+ return total_energy;
+}
+
+/*
* Detect M:N waker/wakee relationships via a switching-frequency heuristic.
*
* A waker of many should wake a different task than the one last awakened
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 22b7cfd..75dcd85 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -893,6 +893,7 @@ static inline struct sched_domain *lowest_flag_domain(int cpu, int flag)
DECLARE_PER_CPU(struct sched_domain *, sd_numa);
DECLARE_PER_CPU(struct sched_domain *, sd_asym);
DECLARE_PER_CPU(struct sched_domain *, sd_ea);
+DECLARE_PER_CPU(struct sched_domain *, sd_scs);
struct sched_group_capacity {
atomic_t ref;
--
1.9.1
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