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>

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2863d223c07effb6efcceaec2e6395aa18246d95..45e54b0e3669c9b942391c63adb98313adc9d55e 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5993,11 +5993,12 @@ DEFINE_PER_CPU(int, sd_llc_id);
 DEFINE_PER_CPU(struct sched_domain *, sd_numa);
 DEFINE_PER_CPU(struct sched_domain *, sd_busy);
 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 *sd;
-       struct sched_domain *busy_sd = NULL;
+       struct sched_domain *busy_sd = NULL, *ea_sd = NULL;
        int id = cpu;
        int size = 1;
 
@@ -6018,6 +6019,14 @@ 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);
 }
 
 /*

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 1813cba2995d752a9ba423025baf0fda23bd9b84..a77516a15ba019c955a81722956eda85cd6e636b 100644 (file)
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -839,6 +839,7 @@ DECLARE_PER_CPU(int, sd_llc_id);
 DECLARE_PER_CPU(struct sched_domain *, sd_numa);
 DECLARE_PER_CPU(struct sched_domain *, sd_busy);
 DECLARE_PER_CPU(struct sched_domain *, sd_asym);
+DECLARE_PER_CPU(struct sched_domain *, sd_ea);
 
 struct sched_group_capacity {
        atomic_t ref;