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From: Matt Fleming <matt@codeblueprint.co.uk>
To: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>
Cc: Byungchul Park <byungchul.park@lge.com>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Luca Abeni <luca.abeni@unitn.it>, Rik van Riel <riel@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Wanpeng Li <wanpeng.li@hotmail.com>,
	Yuyang Du <yuyang.du@intel.com>, Petr Mladek <pmladek@suse.com>,
	Jan Kara <jack@suse.cz>,
	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
	linux-kernel@vger.kernel.org,
	Mel Gorman <mgorman@techsingularity.net>,
	Mike Galbraith <umgwanakikbuti@gmail.com>,
	Matt Fleming <matt@codeblueprint.co.uk>
Subject: [PATCH v2 6/7] sched/fair: Push rq lock pin/unpin into idle_balance()
Date: Wed, 21 Sep 2016 14:38:12 +0100
Message-ID: <20160921133813.31976-7-matt@codeblueprint.co.uk> (raw)
In-Reply-To: <20160921133813.31976-1-matt@codeblueprint.co.uk>

Future patches will emit warnings if rq_clock() is called before
update_rq_clock() inside a rq_pin_lock()/rq_unpin_lock() pair.

Since there is only one caller of idle_balance() we can push the
unpin/repin there.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
---
 kernel/sched/fair.c | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index f0032827fb79..df9a5b16e1df 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3232,7 +3232,7 @@ static inline unsigned long cfs_rq_load_avg(struct cfs_rq *cfs_rq)
 	return cfs_rq->avg.load_avg;
 }
 
-static int idle_balance(struct rq *this_rq);
+static int idle_balance(struct rq *this_rq, struct rq_flags *rf);
 
 #else /* CONFIG_SMP */
 
@@ -3261,7 +3261,7 @@ attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
 static inline void
 detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
 
-static inline int idle_balance(struct rq *rq)
+static inline int idle_balance(struct rq *rq, struct rq_flags *rf)
 {
 	return 0;
 }
@@ -5825,15 +5825,8 @@ simple:
 	return p;
 
 idle:
-	/*
-	 * This is OK, because current is on_cpu, which avoids it being picked
-	 * for load-balance and preemption/IRQs are still disabled avoiding
-	 * further scheduler activity on it and we're being very careful to
-	 * re-start the picking loop.
-	 */
-	rq_unpin_lock(rq, rf);
-	new_tasks = idle_balance(rq);
-	rq_repin_lock(rq, rf);
+	new_tasks = idle_balance(rq, rf);
+
 	/*
 	 * Because idle_balance() releases (and re-acquires) rq->lock, it is
 	 * possible for any higher priority task to appear. In that case we
@@ -7767,7 +7760,7 @@ update_next_balance(struct sched_domain *sd, unsigned long *next_balance)
  * idle_balance is called by schedule() if this_cpu is about to become
  * idle. Attempts to pull tasks from other CPUs.
  */
-static int idle_balance(struct rq *this_rq)
+static int idle_balance(struct rq *this_rq, struct rq_flags *rf)
 {
 	unsigned long next_balance = jiffies + HZ;
 	int this_cpu = this_rq->cpu;
@@ -7781,6 +7774,14 @@ static int idle_balance(struct rq *this_rq)
 	 */
 	this_rq->idle_stamp = rq_clock(this_rq);
 
+	/*
+	 * This is OK, because current is on_cpu, which avoids it being picked
+	 * for load-balance and preemption/IRQs are still disabled avoiding
+	 * further scheduler activity on it and we're being very careful to
+	 * re-start the picking loop.
+	 */
+	rq_unpin_lock(this_rq, rf);
+
 	if (this_rq->avg_idle < sysctl_sched_migration_cost ||
 	    !this_rq->rd->overload) {
 		rcu_read_lock();
@@ -7858,6 +7859,8 @@ out:
 	if (pulled_task)
 		this_rq->idle_stamp = 0;
 
+	rq_repin_lock(this_rq, rf);
+
 	return pulled_task;
 }
 
-- 
2.9.3

  parent reply index

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-21 13:38 [PATCH v2 0/7] sched: Diagnostic checks for missing rq clock updates Matt Fleming
2016-09-21 13:38 ` [PATCH v2 1/7] sched/fair: Update the rq clock before detaching tasks Matt Fleming
2016-10-03 12:49   ` Peter Zijlstra
2016-10-03 14:37     ` Matt Fleming
2016-10-03 14:42       ` Peter Zijlstra
2016-09-21 13:38 ` [PATCH v2 2/7] sched/fair: Update rq clock before waking up new task Matt Fleming
2016-09-21 13:38 ` [PATCH v2 3/7] sched/fair: Update rq clock in task_hot() Matt Fleming
2016-09-21 13:38 ` [PATCH v2 4/7] sched: Add wrappers for lockdep_(un)pin_lock() Matt Fleming
2017-01-14 12:40   ` [tip:sched/core] sched/core: " tip-bot for Matt Fleming
2016-09-21 13:38 ` [PATCH v2 5/7] sched/core: Reset RQCF_ACT_SKIP before unpinning rq->lock Matt Fleming
2017-01-14 12:41   ` [tip:sched/core] " tip-bot for Matt Fleming
2016-09-21 13:38 ` Matt Fleming [this message]
2017-01-14 12:41   ` [tip:sched/core] sched/fair: Push rq lock pin/unpin into idle_balance() tip-bot for Matt Fleming
2016-09-21 13:38 ` [PATCH v2 7/7] sched/core: Add debug code to catch missing update_rq_clock() Matt Fleming
2016-09-21 15:58   ` Petr Mladek
2016-09-21 19:08     ` Matt Fleming
2016-09-21 19:46       ` Thomas Gleixner
2016-09-22  0:44       ` Sergey Senozhatsky
2016-09-22  8:04     ` Peter Zijlstra
2016-09-22  8:36       ` Jan Kara
2016-09-22  9:39         ` Peter Zijlstra
2016-09-22 10:17           ` Peter Zijlstra
2017-01-14 12:44   ` [tip:sched/core] sched/core: Add debugging code to catch missing update_rq_clock() calls tip-bot for Matt Fleming
     [not found]     ` <87tw8gutp6.fsf@concordia.ellerman.id.au>
2017-01-30 21:34       ` Matt Fleming
2017-01-31  8:35         ` Michael Ellerman
2017-01-31 11:00         ` Sachin Sant
2017-01-31 11:48           ` Mike Galbraith
2017-01-31 17:22             ` Ross Zwisler
2017-02-02 15:55               ` Peter Zijlstra
2017-02-02 22:01                 ` Matt Fleming
2017-02-03  3:05                 ` Mike Galbraith
2017-02-03  4:33                 ` Sachin Sant
2017-02-03  8:53                   ` Peter Zijlstra
2017-02-03 12:59                     ` Mike Galbraith
2017-02-03 13:37                       ` Peter Zijlstra
2017-02-03 13:52                         ` Mike Galbraith
2017-02-03 15:44                         ` Paul E. McKenney
2017-02-03 15:54                           ` Paul E. McKenney
2017-02-06  6:23                             ` Sachin Sant
2017-02-06 15:10                               ` Paul E. McKenney
2017-02-06 15:14                                 ` Paul E. McKenney
2017-02-03 13:04                 ` Borislav Petkov
2017-02-22  9:03                 ` Wanpeng Li
2017-02-24  9:16                 ` [tip:sched/urgent] sched/core: Fix update_rq_clock() splat on hotplug (and suspend/resume) tip-bot for Peter Zijlstra

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