sched: Highest energy aware balancing sched_domain level pointer

Add another member to the family of per-cpu sched_domain shortcut
pointers. This one, sd_ea, points to the highest level at which energy
model is provided. At this level and all levels below all sched_groups
have energy model data attached.

Partial energy model information is possible but restricted to providing
energy model data for lower level sched_domains (sd_ea and below) and
leaving load-balancing on levels above to non-energy-aware
load-balancing. For example, it is possible to apply energy-aware
scheduling within each socket on a multi-socket system and let normal
scheduling handle load-balancing between sockets.

cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index e6fc0361181e445f92daea4b7b6c0bc1c44fc4ee..53d7b0340947191f87272f3bf730f6f44adbaa4c 100644 (file)
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1074,6 +1074,7 @@ DECLARE_PER_CPU(int, sd_llc_id);
 DECLARE_PER_CPU(struct sched_domain_shared *, sd_llc_shared);
 DECLARE_PER_CPU(struct sched_domain *, sd_numa);
 DECLARE_PER_CPU(struct sched_domain *, sd_asym);
+DECLARE_PER_CPU(struct sched_domain *, sd_ea);
 
 struct sched_group_capacity {
        atomic_t ref;

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 61760b846d5e7a010c4ab5d8fe5544628b661e77..64f6c6c58000f10c09e6da096ed1cc67507461f0 100644 (file)
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -413,11 +413,13 @@ DEFINE_PER_CPU(int, sd_llc_id);
 DEFINE_PER_CPU(struct sched_domain_shared *, sd_llc_shared);
 DEFINE_PER_CPU(struct sched_domain *, sd_numa);
 DEFINE_PER_CPU(struct sched_domain *, sd_asym);
+DEFINE_PER_CPU(struct sched_domain *, sd_ea);
 
 static void update_top_cache_domain(int cpu)
 {
        struct sched_domain_shared *sds = NULL;
        struct sched_domain *sd;
+       struct sched_domain *ea_sd = NULL;
        int id = cpu;
        int size = 1;
 
@@ -438,6 +440,14 @@ static void update_top_cache_domain(int cpu)
 
        sd = highest_flag_domain(cpu, SD_ASYM_PACKING);
        rcu_assign_pointer(per_cpu(sd_asym, cpu), sd);
+
+       for_each_domain(cpu, sd) {
+               if (sd->groups->sge)
+                       ea_sd = sd;
+               else
+                       break;
+       }
+       rcu_assign_pointer(per_cpu(sd_ea, cpu), ea_sd);
 }
 
 /*