linux-kernel - [PATCH 09/14] sched: evaluate the activity level of the system

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Date:	Thu, 25 Apr 2013 19:23:25 +0200
From:	Vincent Guittot <vincent.guittot@...aro.org>
To:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linaro-kernel@...ts.linaro.org, peterz@...radead.org,
	mingo@...nel.org, linux@....linux.org.uk, pjt@...gle.com,
	santosh.shilimkar@...com, Morten.Rasmussen@....com,
	chander.kashyap@...aro.org, cmetcalf@...era.com,
	tony.luck@...el.com, alex.shi@...el.com, preeti@...ux.vnet.ibm.com
Cc:	paulmck@...ux.vnet.ibm.com, tglx@...utronix.de,
	len.brown@...el.com, arjan@...ux.intel.com,
	amit.kucheria@...aro.org, corbet@....net, l.majewski@...sung.com,
	Vincent Guittot <vincent.guittot@...aro.org>
Subject: [PATCH 09/14] sched: evaluate the activity level of the system

We evaluate the activity level of CPUs, groups and domains in order to define
how many CPUs are required to handle the current activity.

Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
---
 kernel/sched/fair.c |   19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 954adfd..234ecdd 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3465,7 +3465,22 @@ static int check_pack_buddy(int cpu, struct task_struct *p)
 		return true;
 
 	return false;
+}
+
+static int get_cpu_activity(int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+	u32 sum = rq->avg.runnable_avg_sum;
+	u32 period = rq->avg.runnable_avg_period;
+
+	sum = min(sum, period);
+
+	if (sum == period) {
+		u32 overload = rq->nr_running > 1 ? 1 : 0;
+		return power_of(cpu) + overload;
+	}
 
+	return (sum * power_of(cpu)) / period;
 }
 
 /*
@@ -4355,6 +4370,7 @@ struct sd_lb_stats {
 	struct sched_group *busiest; /* Busiest group in this sd */
 	struct sched_group *this;  /* Local group in this sd */
 	unsigned long total_load;  /* Total load of all groups in sd */
+	unsigned long total_activity;  /* Total activity of all groups in sd */
 	unsigned long total_pwr;   /*	Total power of all groups in sd */
 	unsigned long avg_load;	   /* Average load across all groups in sd */
 
@@ -4383,6 +4399,7 @@ struct sd_lb_stats {
 struct sg_lb_stats {
 	unsigned long avg_load; /*Avg load across the CPUs of the group */
 	unsigned long group_load; /* Total load over the CPUs of the group */
+	unsigned long group_activity; /* Total activity of the group */
 	unsigned long sum_nr_running; /* Nr tasks running in the group */
 	unsigned long sum_weighted_load; /* Weighted load of group's tasks */
 	unsigned long group_capacity;
@@ -4629,6 +4646,7 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 		}
 
 		sgs->group_load += load;
+		sgs->group_activity += get_cpu_activity(i);
 		sgs->sum_nr_running += nr_running;
 		sgs->sum_weighted_load += weighted_cpuload(i);
 		if (idle_cpu(i))
@@ -4752,6 +4770,7 @@ static inline void update_sd_lb_stats(struct lb_env *env,
 			return;
 
 		sds->total_load += sgs.group_load;
+		sds->total_activity += sgs.group_activity;
 		sds->total_pwr += sg->sgp->power;
 
 		/*
-- 
1.7.9.5

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