From 2359e465f1f15ff9e3f7c59ea70442f6ae54e4a5 Mon Sep 17 00:00:00 2001 From: Morten Rasmussen Date: Fri, 23 Jan 2015 14:20:38 +0000 Subject: sched: Bias new task wakeups towards higher capacity cpus 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 cc: Peter Zijlstra Signed-off-by: Morten Rasmussen --- 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 646744664884..a76777fa6079 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4659,6 +4659,7 @@ 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; @@ -4666,7 +4667,7 @@ 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; @@ -4680,6 +4681,7 @@ 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 */ @@ -4689,6 +4691,9 @@ 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 */ @@ -4696,14 +4701,20 @@ 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; } -- cgit v1.2.3