From: Morten Rasmussen <morten.rasmussen@arm.com>
To: peterz@infradead.org, mingo@redhat.com
Cc: dietmar.eggemann@arm.com, yuyang.du@intel.com,
vincent.guittot@linaro.org, mgalbraith@suse.de,
sgurrappadi@nvidia.com, freedom.tan@mediatek.com,
keita.kobayashi.ym@renesas.com, linux-kernel@vger.kernel.org,
Morten Rasmussen <morten.rasmussen@arm.com>
Subject: [PATCH v4 3/5] sched: Add per-cpu min capacity to sched_group_capacity
Date: Wed, 31 Aug 2016 11:52:17 +0100 [thread overview]
Message-ID: <1472640739-8778-4-git-send-email-morten.rasmussen@arm.com> (raw)
In-Reply-To: <1472640739-8778-1-git-send-email-morten.rasmussen@arm.com>
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
next prev parent reply other threads:[~2016-08-31 10:52 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-31 10:52 [PATCH v4 0/5] sched: Clean-ups and asymmetric cpu capacity support Morten Rasmussen
2016-08-31 10:52 ` [PATCH v4 1/5] sched/fair: Compute task/cpu utilization at wake-up correctly Morten Rasmussen
2016-08-31 10:52 ` [PATCH v4 2/5] sched/fair: Consider spare capacity in find_idlest_group() Morten Rasmussen
2016-08-31 10:52 ` Morten Rasmussen [this message]
2016-08-31 10:52 ` [PATCH v4 4/5] sched/fair: Avoid pulling tasks from non-overloaded higher capacity groups Morten Rasmussen
2016-08-31 10:52 ` [PATCH v4 5/5] sched/fair: Track peak per-entity utilization Morten Rasmussen
2016-09-01 11:51 ` Patrick Bellasi
2016-09-01 12:43 ` Morten Rasmussen
2016-09-01 8:33 ` [PATCH v4 0/5] sched: Clean-ups and asymmetric cpu capacity support Morten Rasmussen
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