The current sg->min_capacity tracks the lowest per-cpu compute capacity available in the sched_group when rt/irq pressure is taken into account. Minimum capacity isn't the ideal metric for tracking if a sched_group needs offloading to another sched_group for some scenarios, e.g. a sched_group with multiple cpus if only one is under heavy pressure. Tracking maximum capacity isn't perfect either but a better choice for some situations as it indicates that the sched_group definitely compute capacity constrained either due to rt/irq pressure on all cpus or asymmetric cpu capacities (e.g. big.LITTLE).
cc: Ingo Molnar <[email protected]> cc: Peter Zijlstra <[email protected]> Signed-off-by: Morten Rasmussen <[email protected]> --- kernel/sched/fair.c | 24 ++++++++++++++++++++---- kernel/sched/sched.h | 1 + kernel/sched/topology.c | 2 ++ 3 files changed, 23 insertions(+), 4 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ed7eb2ac068f..6af3354e9e26 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -7929,13 +7929,14 @@ static void update_cpu_capacity(struct sched_domain *sd, int cpu) cpu_rq(cpu)->cpu_capacity = capacity; sdg->sgc->capacity = capacity; sdg->sgc->min_capacity = capacity; + sdg->sgc->max_capacity = capacity; } void update_group_capacity(struct sched_domain *sd, int cpu) { struct sched_domain *child = sd->child; struct sched_group *group, *sdg = sd->groups; - unsigned long capacity, min_capacity; + unsigned long capacity, min_capacity, max_capacity; unsigned long interval; interval = msecs_to_jiffies(sd->balance_interval); @@ -7949,6 +7950,7 @@ void update_group_capacity(struct sched_domain *sd, int cpu) capacity = 0; min_capacity = ULONG_MAX; + max_capacity = 0; if (child->flags & SD_OVERLAP) { /* @@ -7979,6 +7981,7 @@ void update_group_capacity(struct sched_domain *sd, int cpu) } min_capacity = min(capacity, min_capacity); + max_capacity = max(capacity, max_capacity); } } else { /* @@ -7992,12 +7995,14 @@ void update_group_capacity(struct sched_domain *sd, int cpu) capacity += sgc->capacity; min_capacity = min(sgc->min_capacity, min_capacity); + max_capacity = max(sgc->max_capacity, max_capacity); group = group->next; } while (group != child->groups); } sdg->sgc->capacity = capacity; sdg->sgc->min_capacity = min_capacity; + sdg->sgc->max_capacity = max_capacity; } /* @@ -8093,16 +8098,27 @@ group_is_overloaded(struct lb_env *env, struct sg_lb_stats *sgs) } /* - * group_smaller_cpu_capacity: Returns true if sched_group sg has smaller + * group_smaller_min_cpu_capacity: Returns true if sched_group sg has smaller * per-CPU capacity than sched_group ref. */ static inline bool -group_smaller_cpu_capacity(struct sched_group *sg, struct sched_group *ref) +group_smaller_min_cpu_capacity(struct sched_group *sg, struct sched_group *ref) { return sg->sgc->min_capacity * capacity_margin < ref->sgc->min_capacity * 1024; } +/* + * group_smaller_max_cpu_capacity: Returns true if sched_group sg has smaller + * per-CPU capacity_orig than sched_group ref. + */ +static inline bool +group_smaller_max_cpu_capacity(struct sched_group *sg, struct sched_group *ref) +{ + return sg->sgc->max_capacity * capacity_margin < + ref->sgc->max_capacity * 1024; +} + static inline enum group_type group_classify(struct sched_group *group, struct sg_lb_stats *sgs) @@ -8248,7 +8264,7 @@ static bool update_sd_pick_busiest(struct lb_env *env, * power/energy consequences are not considered. */ if (sgs->sum_nr_running <= sgs->group_weight && - group_smaller_cpu_capacity(sds->local, sg)) + group_smaller_min_cpu_capacity(sds->local, sg)) return false; asym_packing: diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 273d07dedc90..5ed67122cf59 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1165,6 +1165,7 @@ struct sched_group_capacity { */ unsigned long capacity; unsigned long min_capacity; /* Min per-CPU capacity in group */ + unsigned long max_capacity; /* Max per-CPU capacity in group */ unsigned long next_update; int imbalance; /* XXX unrelated to capacity but shared group state */ diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index edc87e35fc75..f32bf3a998b1 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -708,6 +708,7 @@ static void init_overlap_sched_group(struct sched_domain *sd, sg_span = sched_group_span(sg); sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span); sg->sgc->min_capacity = SCHED_CAPACITY_SCALE; + sg->sgc->max_capacity = SCHED_CAPACITY_SCALE; } static int @@ -867,6 +868,7 @@ static struct sched_group *get_group(int cpu, struct sd_data *sdd) sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sched_group_span(sg)); sg->sgc->min_capacity = SCHED_CAPACITY_SCALE; + sg->sgc->max_capacity = SCHED_CAPACITY_SCALE; return sg; } -- 2.7.4
