linux-kernel - [PATCH 06/19] smart: use CPU selection logic if smart is enabled

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Date:	Thu,  4 Sep 2014 20:30:52 +0400
From:	klamm@...dex-team.ru
To:	peterz@...radead.org, mingo@...hat.com,
	linux-kernel@...r.kernel.org
Cc:	stfomichev@...dex-team.ru, Roman Gushchin <klamm@...dex-team.ru>
Subject: [PATCH 06/19] smart: use CPU selection logic if smart is enabled

From: Roman Gushchin <klamm@...dex-team.ru>

This patch causes rt scheduler to use smart CPU selection logic,
if smart_enabled() returns true.

Also, release_core() should be called every time rt-task is actually
enqueued on the runqueue or it's clear, that it will never be enqueued
on selected CPU.

Signed-off-by: Roman Gushchin <klamm@...dex-team.ru>
---
 kernel/sched/core.c |  6 +++++-
 kernel/sched/rt.c   | 29 +++++++++++++++++++++++++++--
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 14bcdd6..832b3d0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1262,8 +1262,12 @@ int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags)
 	 *   not worry about this generic constraint ]
 	 */
 	if (unlikely(!cpumask_test_cpu(cpu, tsk_cpus_allowed(p)) ||
-		     !cpu_online(cpu)))
+		     !cpu_online(cpu))) {
+		if (smart_enabled() && task_has_rt_policy(p) && cpu >= 0)
+			release_core(cpu);
+
 		cpu = select_fallback_rq(task_cpu(p), p);
+	}
 
 	return cpu;
 }
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 805951b..1993c47 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -15,6 +15,14 @@ struct static_key __smart_enabled = STATIC_KEY_INIT_TRUE;
 DEFINE_MUTEX(smart_mutex);
 
 DEFINE_PER_CPU_SHARED_ALIGNED(struct smart_core_data, smart_core_data);
+
+static int smart_find_lowest_rq(struct task_struct *task, bool wakeup);
+
+#else /* CONFIG_SMART */
+static inline int smart_find_lowest_rq(struct task_struct *task, bool wakeup)
+{
+	return -1;
+}
 #endif /* CONFIG_SMART */
 
 int sched_rr_timeslice = RR_TIMESLICE;
@@ -1211,6 +1219,7 @@ enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
 		enqueue_pushable_task(rq, p);
 
 	inc_nr_running(rq);
+	release_core(cpu_of(rq));
 }
 
 static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
@@ -1278,6 +1287,13 @@ select_task_rq_rt(struct task_struct *p, int sd_flag, int flags)
 	if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
 		goto out;
 
+	if (smart_enabled()) {
+		int target = smart_find_lowest_rq(p, true);
+		if (likely(target != -1))
+			cpu = target;
+		goto out;
+	}
+
 	rq = cpu_rq(cpu);
 
 	rcu_read_lock();
@@ -1580,10 +1596,17 @@ static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
 	int cpu;
 
 	for (tries = 0; tries < RT_MAX_TRIES; tries++) {
-		cpu = find_lowest_rq(task);
+		if (smart_enabled())
+			cpu = smart_find_lowest_rq(task, false);
+		else
+			cpu = find_lowest_rq(task);
+
+		if ((cpu == -1) || (cpu == rq->cpu)) {
+			if (cpu == rq->cpu)
+				release_core(cpu);
 
-		if ((cpu == -1) || (cpu == rq->cpu))
 			break;
+		}
 
 		lowest_rq = cpu_rq(cpu);
 
@@ -1602,6 +1625,7 @@ static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
 				     !task->on_rq)) {
 
 				double_unlock_balance(rq, lowest_rq);
+				release_core(cpu);
 				lowest_rq = NULL;
 				break;
 			}
@@ -1614,6 +1638,7 @@ static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
 		/* try again */
 		double_unlock_balance(rq, lowest_rq);
 		lowest_rq = NULL;
+		release_core(cpu);
 	}
 
 	return lowest_rq;
-- 
1.9.3

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