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Message-Id: <1404404770-323-8-git-send-email-morten.rasmussen@arm.com>
Date: Thu, 3 Jul 2014 17:25:54 +0100
From: Morten Rasmussen <morten.rasmussen@....com>
To: linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
peterz@...radead.org, mingo@...nel.org
Cc: rjw@...ysocki.net, vincent.guittot@...aro.org,
daniel.lezcano@...aro.org, preeti@...ux.vnet.ibm.com,
Dietmar.Eggemann@....com, pjt@...gle.com
Subject: [RFCv2 PATCH 07/23] sched: Introduce system-wide sched_energy
From: Dietmar Eggemann <dietmar.eggemann@....com>
The energy aware algorithm needs system wide energy information on certain
platforms (e.g. a one socket SMP system). Unfortunately, there is no
sched_group that covers all cpus in the system, so there is no place to
attach a system wide sched_group_energy data structure. In such a system,
the energy data is only attached to the sched groups for the individual
cpus in the sched domain (sd) MC level.
This patch adds a _hack_ to provide system-wide energy data via the
sched_domain_topology_level table for such a system.
The problem is that the sched_domain_topology_level table is not an
interface to provide system-wide data but we want to keep the
configuration of all energy related data in one place.
The sched_domain_energy_f of the last entry (the one which is
initialized with {NULL, }) of the sched_domain_topology_level table is
set to cpu_sys_energy(). Since the sched_domain_mask_f of this entry
stays NULL it is still not considered for the existing scheduler set-up
code (see for_each_sd_topology()).
A second call to init_sched_energy() with an sd pointer argument set to
NULL initializes the system-wide energy structure sse.
There is no system-wide power management on the example platform (ARM TC2)
which could potentially interact with the scheduler so struct
sched_group_energy *sse stays NULL.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@....com>
---
arch/arm/kernel/topology.c | 7 ++++++-
kernel/sched/core.c | 34 ++++++++++++++++++++++++++++++----
kernel/sched/sched.h | 2 ++
3 files changed, 38 insertions(+), 5 deletions(-)
diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
index a7d5a6e..70915b1 100644
--- a/arch/arm/kernel/topology.c
+++ b/arch/arm/kernel/topology.c
@@ -386,6 +386,11 @@ static inline const struct sched_group_energy *cpu_core_energy(int cpu)
&energy_core_a15;
}
+static inline const struct sched_group_energy *cpu_sys_energy(int cpu)
+{
+ return NULL;
+}
+
static inline const int cpu_corepower_flags(void)
{
return SD_SHARE_PKG_RESOURCES | SD_SHARE_POWERDOMAIN;
@@ -396,7 +401,7 @@ static struct sched_domain_topology_level arm_topology[] = {
{ cpu_coregroup_mask, cpu_corepower_flags, cpu_core_energy, SD_INIT_NAME(MC) },
#endif
{ cpu_cpu_mask, 0, cpu_cluster_energy, SD_INIT_NAME(DIE) },
- { NULL, },
+ { NULL, 0, cpu_sys_energy},
};
/*
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7fecc63..2d7544a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5954,20 +5954,44 @@ static void init_sched_groups_capacity(int cpu, struct sched_domain *sd)
atomic_set(&sg->sgc->nr_busy_cpus, sg->group_weight);
}
+/* System-wide energy information. */
+struct sched_group_energy *sse;
+
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;
+ struct sched_group *sg = sd ? sd->groups : NULL;
+ struct sched_group_energy *energy = sd ? sg->sge : sse;
sched_domain_energy_f fn = tl->energy;
- struct cpumask *mask = sched_group_cpus(sg);
+ const struct cpumask *mask = sd ? sched_group_cpus(sg) :
+ cpu_cpu_mask(cpu);
- if (!fn || !fn(cpu))
+ if (!fn || !fn(cpu) || (!sd && energy))
return;
if (cpumask_weight(mask) > 1)
check_sched_energy_data(cpu, fn, mask);
+ if (!sd) {
+ energy = sse = kzalloc(sizeof(struct sched_group_energy) +
+ fn(cpu)->nr_idle_states*
+ sizeof(struct idle_state) +
+ fn(cpu)->nr_cap_states*
+ sizeof(struct capacity_state),
+ GFP_KERNEL);
+ BUG_ON(!energy);
+
+ energy->idle_states = (struct idle_state *)
+ ((void *)&energy->cap_states +
+ sizeof(energy->cap_states));
+
+ energy->cap_states = (struct capacity_state *)
+ ((void *)&energy->cap_states +
+ sizeof(energy->cap_states) +
+ fn(cpu)->nr_idle_states*
+ sizeof(struct idle_state));
+ }
+
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));
@@ -6655,6 +6679,8 @@ static int build_sched_domains(const struct cpumask *cpu_map,
claim_allocations(i, sd);
init_sched_groups_capacity(i, sd);
}
+
+ init_sched_energy(i, NULL, tl);
}
/* Attach the domains */
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 1a5f1ee..c971359 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -747,6 +747,8 @@ struct sched_group_capacity {
unsigned long cpumask[0]; /* iteration mask */
};
+extern struct sched_group_energy *sse;
+
struct sched_group {
struct sched_group *next; /* Must be a circular list */
atomic_t ref;
--
1.7.9.5
--
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