[RFC PATCH 09/10] sched: Include blocked utilization in usage tracking

From: Morten Rasmussen
Date: Tue Dec 02 2014 - 09:09:11 EST


Add the blocked utilization contribution to group sched_entity
utilization (se->avg.utilization_avg_contrib) and to get_cpu_usage().
With this change cpu usage now includes recent usage by currently
non-runnable tasks, hence it provides a more stable view of the cpu
usage. It does, however, also mean that the meaning of usage is changed:
A cpu may be momentarily idle while usage >0. It can no longer be
assumed that cpu usage >0 implies runnable tasks on the rq.
cfs_rq->utilization_load_avg or nr_running should be used instead to get
the current rq status.

cc: Ingo Molnar <mingo@xxxxxxxxxx>
cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

Signed-off-by: Morten Rasmussen <morten.rasmussen@xxxxxxx>
---
kernel/sched/fair.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index adf64df..bd950b2 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2764,7 +2764,8 @@ static long __update_entity_utilization_avg_contrib(struct sched_entity *se)
__update_task_entity_utilization(se);
else
se->avg.utilization_avg_contrib =
- group_cfs_rq(se)->utilization_load_avg;
+ group_cfs_rq(se)->utilization_load_avg +
+ group_cfs_rq(se)->utilization_blocked_avg;

return se->avg.utilization_avg_contrib - old_contrib;
}
@@ -4827,11 +4828,12 @@ static int select_idle_sibling(struct task_struct *p, int target)
static int get_cpu_usage(int cpu)
{
unsigned long usage = cpu_rq(cpu)->cfs.utilization_load_avg;
+ unsigned long blocked = cpu_rq(cpu)->cfs.utilization_blocked_avg;

- if (usage >= SCHED_LOAD_SCALE)
+ if (usage + blocked >= SCHED_LOAD_SCALE)
return capacity_orig_of(cpu);

- return usage;
+ return usage + blocked;
}

/*
--
1.9.1


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