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UPSTREAM: sched/fair: Add per-CPU min capacity to sched_group_capacity

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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).

Change-Id: I833725e2b70794384c2b8efac5dc8107f1dbb622
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1476452472-24740-4-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit bf475ce0a3)
[Fixed cherry-pick issue]
Signed-off-by: Quentin Perret <quentin.perret@arm.com>
This commit is contained in:
Morten Rasmussen
2016-10-14 14:41:09 +01:00
committed by Andres Oportus
parent 544443501e
commit 3d8cb903db
3 changed files with 8 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
kernel/sched/core.c
View File

@@ -6386,6 +6386,7 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu)
*/
sg->sgc->capacity = SCHED_CAPACITY_SCALE * cpumask_weight(sg_span);
sg->sgc->max_capacity = SCHED_CAPACITY_SCALE;
sg->sgc->min_capacity = SCHED_CAPACITY_SCALE;
/*
* Make sure the first group of this domain contains the

7
kernel/sched/fair.c
View File

@@ -7688,13 +7688,14 @@ skip_unlock: __attribute__ ((unused));
cpu_rq(cpu)->cpu_capacity = capacity;
sdg->sgc->capacity = capacity;
sdg->sgc->max_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, max_capacity;
unsigned long capacity, max_capacity, min_capacity;
unsigned long interval;
interval = msecs_to_jiffies(sd->balance_interval);
@@ -7708,6 +7709,7 @@ void update_group_capacity(struct sched_domain *sd, int cpu)
capacity = 0;
max_capacity = 0;
min_capacity = ULONG_MAX;
if (child->flags & SD_OVERLAP) {
/*
@@ -7738,6 +7740,7 @@ void update_group_capacity(struct sched_domain *sd, int cpu)
}
max_capacity = max(capacity, max_capacity);
min_capacity = min(capacity, min_capacity);
}
} else {
/*
@@ -7751,12 +7754,14 @@ void update_group_capacity(struct sched_domain *sd, int cpu)
capacity += sgc->capacity;
max_capacity = max(sgc->max_capacity, max_capacity);
min_capacity = min(sgc->min_capacity, min_capacity);
group = group->next;
} while (group != child->groups);
}
sdg->sgc->capacity = capacity;
sdg->sgc->max_capacity = max_capacity;
sdg->sgc->min_capacity = min_capacity;
}
/*

1
kernel/sched/sched.h
View File

@@ -933,6 +933,7 @@ struct sched_group_capacity {
*/
unsigned long capacity;
unsigned long max_capacity; /* Max per-cpu capacity in group */
unsigned long min_capacity; /* Min per-CPU capacity in group */
unsigned long next_update;
int imbalance; /* XXX unrelated to capacity but shared group state */