linux-kernel - [patch v5 06/15] sched: log the cpu utilization at rq

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Message-Id: <1361164062-20111-7-git-send-email-alex.shi@intel.com>
Date:	Mon, 18 Feb 2013 13:07:33 +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,
	morten.rasmussen@....com
Subject: [patch v5 06/15] 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 load weight.

BTW, rq->util can be used for any purposes if needed, not only power
scheduling.

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 7ae4c4c..d220354 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 fcdb21f..b9a34ab 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 7a19792..ac1e107 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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