Make wake-ups of new tasks (find_idlest_group) aware of any differences
in cpu compute capacity so new tasks don't get handed off to a cpus with
lower capacity.
cc: Ingo Molnar <mi...@redhat.com>
cc: Peter Zijlstra <pet...@infradead.org>
Signed-off-by: Morten Rasmussen <morten.rasmus...@arm.com>
---
kernel/sched/fair.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 8713310..4251e75 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4950,6 +4950,7 @@ find_idlest_group(struct sched_domain *sd, struct
task_struct *p,
{
struct sched_group *idlest = NULL, *group = sd->groups;
unsigned long min_load = ULONG_MAX, this_load = 0;
+ unsigned long this_cpu_cap = 0, idlest_cpu_cap = 0;
int load_idx = sd->forkexec_idx;
int imbalance = 100 + (sd->imbalance_pct-100)/2;
@@ -4957,7 +4958,7 @@ find_idlest_group(struct sched_domain *sd, struct
task_struct *p,
load_idx = sd->wake_idx;
do {
- unsigned long load, avg_load;
+ unsigned long load, avg_load, cpu_capacity;
int local_group;
int i;
@@ -4971,6 +4972,7 @@ find_idlest_group(struct sched_domain *sd, struct
task_struct *p,
/* Tally up the load of all CPUs in the group */
avg_load = 0;
+ cpu_capacity = 0;
for_each_cpu(i, sched_group_cpus(group)) {
/* Bias balancing toward cpus of our domain */
@@ -4980,6 +4982,9 @@ find_idlest_group(struct sched_domain *sd, struct
task_struct *p,
load = target_load(i, load_idx);
avg_load += load;
+
+ if (cpu_capacity < capacity_of(i))
+ cpu_capacity = capacity_of(i);
}
/* Adjust by relative CPU capacity of the group */
@@ -4987,14 +4992,20 @@ find_idlest_group(struct sched_domain *sd, struct
task_struct *p,
if (local_group) {
this_load = avg_load;
+ this_cpu_cap = cpu_capacity;
} else if (avg_load < min_load) {
min_load = avg_load;
idlest = group;
+ idlest_cpu_cap = cpu_capacity;
}
} while (group = group->next, group != sd->groups);
- if (!idlest || 100*this_load < imbalance*min_load)
+ if (!idlest)
+ return NULL;
+
+ if (100*this_load < imbalance*min_load && this_cpu_cap >=
idlest_cpu_cap)
return NULL;
+
return idlest;
}
--
1.9.1
--
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