Messages in this thread Patch in this message | | | From | Morten Rasmussen <> | Subject | [PATCH v4 3/5] sched: Add per-cpu min capacity to sched_group_capacity | Date | Wed, 31 Aug 2016 11:52:17 +0100 |
| |
struct sched_group_capacity currently represents the compute capacity sum of all cpus in the sched_group. Unless it is divided by the group_weight to get the average capacity per cpu it hides differences in cpu capacity for mixed capacity systems (e.g. high RT/IRQ utilization or ARM big.LITTLE). But even the average may not be sufficient if the group covers cpus of different capacities. Instead, by extending struct sched_group_capacity to indicate min per-cpu capacity in the group a suitable group for a given task utilization can more easily be found such that cpus with reduced capacity can be avoided for tasks with high utilization (not implemented by this patch).
cc: Ingo Molnar <mingo@redhat.com> cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com> --- kernel/sched/core.c | 3 ++- kernel/sched/fair.c | 17 ++++++++++++----- kernel/sched/sched.h | 3 ++- 3 files changed, 16 insertions(+), 7 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 69243142cad1..4df35c448f41 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5656,7 +5656,7 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level, printk(KERN_CONT " %*pbl", cpumask_pr_args(sched_group_cpus(group))); if (group->sgc->capacity != SCHED_CAPACITY_SCALE) { - printk(KERN_CONT " (cpu_capacity = %d)", + printk(KERN_CONT " (cpu_capacity = %lu)", group->sgc->capacity); } @@ -6125,6 +6125,7 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu) * die on a /0 trap. */ sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span); + sg->sgc->min_capacity = SCHED_CAPACITY_SCALE; /* * Make sure the first group of this domain contains the diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ebe8907119b5..112a6d3f3943 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6714,13 +6714,14 @@ 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; } 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; + unsigned long capacity, min_capacity; unsigned long interval; interval = msecs_to_jiffies(sd->balance_interval); @@ -6733,6 +6734,7 @@ void update_group_capacity(struct sched_domain *sd, int cpu) } capacity = 0; + min_capacity = ULONG_MAX; if (child->flags & SD_OVERLAP) { /* @@ -6757,11 +6759,12 @@ void update_group_capacity(struct sched_domain *sd, int cpu) */ if (unlikely(!rq->sd)) { capacity += capacity_of(cpu); - continue; + } else { + sgc = rq->sd->groups->sgc; + capacity += sgc->capacity; } - sgc = rq->sd->groups->sgc; - capacity += sgc->capacity; + min_capacity = min(capacity, min_capacity); } } else { /* @@ -6771,12 +6774,16 @@ void update_group_capacity(struct sched_domain *sd, int cpu) group = child->groups; do { - capacity += group->sgc->capacity; + struct sched_group_capacity *sgc = group->sgc; + + capacity += sgc->capacity; + min_capacity = min(sgc->min_capacity, min_capacity); group = group->next; } while (group != child->groups); } sdg->sgc->capacity = capacity; + sdg->sgc->min_capacity = min_capacity; } /* diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 420c05d099c3..ef646f542994 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -868,7 +868,8 @@ struct sched_group_capacity { * CPU capacity of this group, SCHED_CAPACITY_SCALE being max capacity * for a single CPU. */ - unsigned int capacity; + unsigned long capacity; + unsigned long min_capacity; /* Min per-cpu capacity in group */ unsigned long next_update; int imbalance; /* XXX unrelated to capacity but shared group state */ /* -- 1.9.1
| |