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

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Message-Id: <1417529192-11579-10-git-send-email-morten.rasmussen@arm.com>
Date:	Tue,  2 Dec 2014 14:06:31 +0000
From:	Morten Rasmussen <morten.rasmussen@....com>
To:	peterz@...radead.org, mingo@...hat.com
Cc:	dietmar.eggemann@....com, vincent.guittot@...aro.org,
	pjt@...gle.com, bsegall@...gle.com, mturquette@...aro.org,
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	Morten Rasmussen <morten.rasmussen@....com>
Subject: [RFC PATCH 09/10] sched: Include blocked utilization in usage tracking

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@...hat.com>
cc: Peter Zijlstra <peterz@...radead.org>

Signed-off-by: Morten Rasmussen <morten.rasmussen@....com>
---
 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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