linux-kernel - [RFCv4 PATCH 26/34] sched: Store system-wide maximum cpu capacity in root domain

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Message-Id: <1431459549-18343-27-git-send-email-morten.rasmussen@arm.com>
Date:	Tue, 12 May 2015 20:39:01 +0100
From:	Morten Rasmussen <morten.rasmussen@....com>
To:	peterz@...radead.org, mingo@...hat.com
Cc:	vincent.guittot@...aro.org,
	Dietmar Eggemann <Dietmar.Eggemann@....com>,
	yuyang.du@...el.com, preeti@...ux.vnet.ibm.com,
	mturquette@...aro.org, rjw@...ysocki.net,
	Juri Lelli <Juri.Lelli@....com>, sgurrappadi@...dia.com,
	pang.xunlei@....com.cn, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, morten.rasmussen@....com
Subject: [RFCv4 PATCH 26/34] sched: Store system-wide maximum cpu capacity in root domain

From: Dietmar Eggemann <dietmar.eggemann@....com>

To be able to compare the capacity of the target cpu with the highest
cpu capacity of the system in the wakeup path, store the system-wide
maximum cpu capacity in the root domain.

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

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@....com>
---
 kernel/sched/core.c  | 8 ++++++++
 kernel/sched/sched.h | 3 +++
 2 files changed, 11 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 8818bf0..d307db8 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6848,6 +6848,7 @@ static int build_sched_domains(const struct cpumask *cpu_map,
 	enum s_alloc alloc_state;
 	struct sched_domain *sd;
 	struct s_data d;
+	struct rq *rq;
 	int i, ret = -ENOMEM;
 
 	alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
@@ -6901,11 +6902,18 @@ static int build_sched_domains(const struct cpumask *cpu_map,
 	/* Attach the domains */
 	rcu_read_lock();
 	for_each_cpu(i, cpu_map) {
+		rq = cpu_rq(i);
 		sd = *per_cpu_ptr(d.sd, i);
 		cpu_attach_domain(sd, d.rd, i);
+
+		if (rq->cpu_capacity_orig > rq->rd->max_cpu_capacity)
+			rq->rd->max_cpu_capacity = rq->cpu_capacity_orig;
 	}
 	rcu_read_unlock();
 
+	rq = cpu_rq(cpumask_first(cpu_map));
+	pr_info("Max cpu capacity: %lu\n", rq->rd->max_cpu_capacity);
+
 	ret = 0;
 error:
 	__free_domain_allocs(&d, alloc_state, cpu_map);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index a5d2d69..95c8ff7 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -553,6 +553,9 @@ struct root_domain {
 	 */
 	cpumask_var_t rto_mask;
 	struct cpupri cpupri;
+
+	/* Maximum cpu capacity in the system. */
+	unsigned long max_cpu_capacity;
 };
 
 extern struct root_domain def_root_domain;
-- 
1.9.1

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