linux-kernel - [PATCH v2 06/13] sched: Store maximum per-cpu capacity in root domain

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Date:	Wed, 22 Jun 2016 18:03:17 +0100
From:	Morten Rasmussen <morten.rasmussen@....com>
To:	peterz@...radead.org, mingo@...hat.com
Cc:	dietmar.eggemann@....com, yuyang.du@...el.com,
	vincent.guittot@...aro.org, mgalbraith@...e.de,
	linux-kernel@...r.kernel.org,
	Morten Rasmussen <morten.rasmussen@....com>
Subject: [PATCH v2 06/13] sched: Store maximum per-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
available cpu capacity, store the maximum per-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>
Signed-off-by: Morten Rasmussen <morten.rasmussen@....com>
---
 kernel/sched/core.c  | 9 +++++++++
 kernel/sched/sched.h | 2 ++
 2 files changed, 11 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fe39118ffdfb..5093765e9930 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6855,6 +6855,7 @@ 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 = NULL;
 	int i, ret = -ENOMEM;
 
 	alloc_state = __visit_domain_allocation_hell(&d, cpu_map);
@@ -6905,11 +6906,19 @@ 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();
 
+	if (rq)
+		pr_info("span: %*pbl (max cpu_capacity = %lu)\n",
+			cpumask_pr_args(cpu_map), 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 72f1f3087b04..3e9904ef224f 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -564,6 +564,8 @@ struct root_domain {
 	 */
 	cpumask_var_t rto_mask;
 	struct cpupri cpupri;
+
+	unsigned long max_cpu_capacity;
 };
 
 extern struct root_domain def_root_domain;
-- 
1.9.1