[RFCv5 PATCH 10/46] sched: Include blocked utilization in usage tracking

Morten Rasmussen
2015-07-07T18:23:40Z

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 is >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@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>

Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
---
kernel/sched/fair.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c26980f..775b0c7 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2804,7 +2804,8 @@ 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;
}
@@ -5061,13 +5062,17 @@ static int select_idle_sibling(struct task_struct *p, int target)

static int get_cpu_usage(int cpu)
{
+ int sum;
unsigned long usage = cpu_rq(cpu)->cfs.utilization_load_avg;
+ unsigned long blocked = cpu_rq(cpu)->cfs.utilization_blocked_avg;
unsigned long capacity_orig = capacity_orig_of(cpu);

- if (usage >= capacity_orig)
+ sum = usage + blocked;
+
+ if (sum >= capacity_orig)
return capacity_orig;

- return usage;
+ return sum;
}

/*
--
1.9.1