linux-kernel - [patch v4 11/18] sched: log the cpu utilization at rq

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Date:	Thu, 24 Jan 2013 11:06:53 +0800
From:	Alex Shi <alex.shi@...el.com>
To:	torvalds@...ux-foundation.org, mingo@...hat.com,
	peterz@...radead.org, tglx@...utronix.de,
	akpm@...ux-foundation.org, arjan@...ux.intel.com, bp@...en8.de,
	pjt@...gle.com, namhyung@...nel.org, efault@....de
Cc:	vincent.guittot@...aro.org, gregkh@...uxfoundation.org,
	preeti@...ux.vnet.ibm.com, viresh.kumar@...aro.org,
	linux-kernel@...r.kernel.org, alex.shi@...el.com
Subject: [patch v4 11/18] sched: log the cpu utilization at rq

The cpu's utilization is to measure how busy is the cpu.
        util = cpu_rq(cpu)->avg.runnable_avg_sum
                / cpu_rq(cpu)->avg.runnable_avg_period;

Since the util is no more than 1, we use its percentage value in later
caculations. And set the the FULL_UTIL as 100%.

In later power aware scheduling, we are sensitive for how busy of the
cpu, not how much weight of its load. As to power consuming, it is more
related with cpu busy time, not the load weight.

Signed-off-by: Alex Shi <alex.shi@...el.com>
---
 kernel/sched/debug.c | 1 +
 kernel/sched/fair.c  | 4 ++++
 kernel/sched/sched.h | 4 ++++
 3 files changed, 9 insertions(+)

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 2cd3c1b..e4035f7 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -318,6 +318,7 @@ do {									\
 
 	P(ttwu_count);
 	P(ttwu_local);
+	P(util);
 
 #undef P
 #undef P64
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 947542f..20363fb 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1495,8 +1495,12 @@ static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update)
 
 static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
 {
+	u32 period;
 	__update_entity_runnable_avg(rq->clock_task, &rq->avg, runnable);
 	__update_tg_runnable_avg(&rq->avg, &rq->cfs);
+
+	period = rq->avg.runnable_avg_period ? rq->avg.runnable_avg_period : 1;
+	rq->util = rq->avg.runnable_avg_sum * 100 / period;
 }
 
 /* Add the load generated by se into cfs_rq's child load-average */
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 66b08a1..fa8bdb9 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -350,6 +350,9 @@ extern struct root_domain def_root_domain;
 
 #endif /* CONFIG_SMP */
 
+/* the percentage full cpu utilization */
+#define FULL_UTIL	100
+
 /*
  * This is the main, per-CPU runqueue data structure.
  *
@@ -481,6 +484,7 @@ struct rq {
 #endif
 
 	struct sched_avg avg;
+	unsigned int util;
 };
 
 static inline int cpu_of(struct rq *rq)
-- 
1.7.12

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