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Subject[RFCv2 PATCH 04/23] sched: Allocate and initialize energy data structures
Date
From: Dietmar Eggemann <dietmar.eggemann@arm.com>

The per sched group (sg) sched_group_energy structure plus the related
idle_state and capacity_state arrays are allocated like the other sched
domain (sd) hierarchy data structures. This includes the freeing of
sched_group_energy structures which are not used.

One problem is that the number of elements of the idle_state and the
capacity_state arrays is not fixed and has to be retrieved in
__sdt_alloc() to allocate memory for the sched_group_energy structure and
the two arrays in one chunk. The array pointers (idle_states and
cap_states) are initialized here to point to the correct place inside the
memory chunk.

The new function init_sched_energy() initializes the sched_group_energy
structure and the two arrays in case the sd topology level contains energy
information.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
---
kernel/sched/core.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++-
kernel/sched/sched.h | 35 +++++++++++++++++++++++++
2 files changed, 105 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 54f5722..ecece17 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5539,6 +5539,7 @@ static void free_sched_domain(struct rcu_head *rcu)
free_sched_groups(sd->groups, 1);
} else if (atomic_dec_and_test(&sd->groups->ref)) {
kfree(sd->groups->sgc);
+ kfree(sd->groups->sge);
kfree(sd->groups);
}
kfree(sd);
@@ -5799,6 +5800,8 @@ static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
*sg = *per_cpu_ptr(sdd->sg, cpu);
(*sg)->sgc = *per_cpu_ptr(sdd->sgc, cpu);
atomic_set(&(*sg)->sgc->ref, 1); /* for claim_allocations */
+ (*sg)->sge = *per_cpu_ptr(sdd->sge, cpu);
+ atomic_set(&(*sg)->sge->ref, 1); /* for claim_allocations */
}

return cpu;
@@ -5888,6 +5891,28 @@ static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
atomic_set(&sg->sgc->nr_busy_cpus, sg->group_weight);
}

+static void init_sched_energy(int cpu, struct sched_domain *sd,
+ struct sched_domain_topology_level *tl)
+{
+ struct sched_group *sg = sd->groups;
+ struct sched_group_energy *energy = sg->sge;
+ sched_domain_energy_f fn = tl->energy;
+ struct cpumask *mask = sched_group_cpus(sg);
+
+ if (!fn || !fn(cpu))
+ return;
+
+ if (cpumask_weight(mask) > 1)
+ check_sched_energy_data(cpu, fn, mask);
+
+ energy->nr_idle_states = fn(cpu)->nr_idle_states;
+ memcpy(energy->idle_states, fn(cpu)->idle_states,
+ energy->nr_idle_states*sizeof(struct idle_state));
+ energy->nr_cap_states = fn(cpu)->nr_cap_states;
+ memcpy(energy->cap_states, fn(cpu)->cap_states,
+ energy->nr_cap_states*sizeof(struct capacity_state));
+}
+
/*
* Initializers for schedule domains
* Non-inlined to reduce accumulated stack pressure in build_sched_domains()
@@ -5978,6 +6003,9 @@ static void claim_allocations(int cpu, struct sched_domain *sd)

if (atomic_read(&(*per_cpu_ptr(sdd->sgc, cpu))->ref))
*per_cpu_ptr(sdd->sgc, cpu) = NULL;
+
+ if (atomic_read(&(*per_cpu_ptr(sdd->sge, cpu))->ref))
+ *per_cpu_ptr(sdd->sge, cpu) = NULL;
}

#ifdef CONFIG_NUMA
@@ -6383,10 +6411,24 @@ static int __sdt_alloc(const struct cpumask *cpu_map)
if (!sdd->sgc)
return -ENOMEM;

+ sdd->sge = alloc_percpu(struct sched_group_energy *);
+ if (!sdd->sge)
+ return -ENOMEM;
+
for_each_cpu(j, cpu_map) {
struct sched_domain *sd;
struct sched_group *sg;
struct sched_group_capacity *sgc;
+ struct sched_group_energy *sge;
+ sched_domain_energy_f fn = tl->energy;
+ unsigned int nr_idle_states = 0;
+ unsigned int nr_cap_states = 0;
+
+ if (fn && fn(j)) {
+ nr_idle_states = fn(j)->nr_idle_states;
+ nr_cap_states = fn(j)->nr_cap_states;
+ BUG_ON(!nr_idle_states || !nr_cap_states);
+ }

sd = kzalloc_node(sizeof(struct sched_domain) + cpumask_size(),
GFP_KERNEL, cpu_to_node(j));
@@ -6410,6 +6452,26 @@ static int __sdt_alloc(const struct cpumask *cpu_map)
return -ENOMEM;

*per_cpu_ptr(sdd->sgc, j) = sgc;
+
+ sge = kzalloc_node(sizeof(struct sched_group_energy) +
+ nr_idle_states*sizeof(struct idle_state) +
+ nr_cap_states*sizeof(struct capacity_state),
+ GFP_KERNEL, cpu_to_node(j));
+
+ if (!sge)
+ return -ENOMEM;
+
+ sge->idle_states = (struct idle_state *)
+ ((void *)&sge->cap_states +
+ sizeof(sge->cap_states));
+
+ sge->cap_states = (struct capacity_state *)
+ ((void *)&sge->cap_states +
+ sizeof(sge->cap_states) +
+ nr_idle_states*
+ sizeof(struct idle_state));
+
+ *per_cpu_ptr(sdd->sge, j) = sge;
}
}

@@ -6438,6 +6500,8 @@ static void __sdt_free(const struct cpumask *cpu_map)
kfree(*per_cpu_ptr(sdd->sg, j));
if (sdd->sgc)
kfree(*per_cpu_ptr(sdd->sgc, j));
+ if (sdd->sge)
+ kfree(*per_cpu_ptr(sdd->sge, j));
}
free_percpu(sdd->sd);
sdd->sd = NULL;
@@ -6445,6 +6509,8 @@ static void __sdt_free(const struct cpumask *cpu_map)
sdd->sg = NULL;
free_percpu(sdd->sgc);
sdd->sgc = NULL;
+ free_percpu(sdd->sge);
+ sdd->sge = NULL;
}
}

@@ -6516,10 +6582,13 @@ static int build_sched_domains(const struct cpumask *cpu_map,

/* Calculate CPU capacity for physical packages and nodes */
for (i = nr_cpumask_bits-1; i >= 0; i--) {
+ struct sched_domain_topology_level *tl = sched_domain_topology;
+
if (!cpumask_test_cpu(i, cpu_map))
continue;

- for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent) {
+ for (sd = *per_cpu_ptr(d.sd, i); sd; sd = sd->parent, tl++) {
+ init_sched_energy(i, sd, tl);
claim_allocations(i, sd);
init_sched_groups_capacity(i, sd);
}
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index d300a64..1a5f1ee 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -790,6 +790,41 @@ static inline unsigned int group_first_cpu(struct sched_group *group)

extern int group_balance_cpu(struct sched_group *sg);

+/*
+ * Check that the per-cpu provided sd energy data is consistent for all cpus
+ * within the mask.
+ */
+static inline void check_sched_energy_data(int cpu, sched_domain_energy_f fn,
+ const struct cpumask *cpumask)
+{
+ struct cpumask mask;
+ int i;
+
+ cpumask_xor(&mask, cpumask, get_cpu_mask(cpu));
+
+ for_each_cpu(i, &mask) {
+ int y;
+
+ BUG_ON(fn(i)->nr_idle_states != fn(cpu)->nr_idle_states);
+
+ for (y = 0; y < (fn(i)->nr_idle_states); y++) {
+ BUG_ON(fn(i)->idle_states[y].power !=
+ fn(cpu)->idle_states[y].power);
+ BUG_ON(fn(i)->idle_states[y].wu_energy !=
+ fn(cpu)->idle_states[y].wu_energy);
+ }
+
+ BUG_ON(fn(i)->nr_cap_states != fn(cpu)->nr_cap_states);
+
+ for (y = 0; y < (fn(i)->nr_cap_states); y++) {
+ BUG_ON(fn(i)->cap_states[y].cap !=
+ fn(cpu)->cap_states[y].cap);
+ BUG_ON(fn(i)->cap_states[y].power !=
+ fn(cpu)->cap_states[y].power);
+ }
+ }
+}
+
#else

static inline void sched_ttwu_pending(void) { }
--
1.7.9.5



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