linux-kernel - [PATCH 1/2] nohz: move NOHZ code bits out of io_schedule{,

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Message-Id: <1398452250-6047-1-git-send-email-dvlasenk@redhat.com>
Date:	Fri, 25 Apr 2014 20:57:29 +0200
From:	Denys Vlasenko <dvlasenk@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	Denys Vlasenko <dvlasenk@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
	Fernando Luis Vazquez Cao <fernando_b1@....ntt.co.jp>,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arjan van de Ven <arjan@...ux.intel.com>,
	Oleg Nesterov <oleg@...hat.com>
Subject: [PATCH 1/2] nohz: move NOHZ code bits out of io_schedule{,_timeout} into a helper

Signed-off-by: Denys Vlasenko <dvlasenk@...hat.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
Cc: Fernando Luis Vazquez Cao <fernando_b1@....ntt.co.jp>
Cc: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Arjan van de Ven <arjan@...ux.intel.com>
Cc: Oleg Nesterov <oleg@...hat.com>
---
 kernel/sched/core.c | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index ffea757..3137980 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4208,6 +4208,21 @@ EXPORT_SYMBOL_GPL(yield_to);
  * This task is about to go to sleep on IO. Increment rq->nr_iowait so
  * that process accounting knows that this is a task in IO wait state.
  */
+#ifdef CONFIG_NO_HZ_COMMON
+static __sched void io_wait_end(struct rq *rq)
+{
+	if (atomic_dec_and_test(&rq->nr_iowait)) {
+		if (raw_smp_processor_id() != cpu_of(rq))
+			tick_nohz_iowait_to_idle(cpu_of(rq));
+	}
+}
+#else
+static inline void io_wait_end(struct rq *rq)
+{
+	atomic_dec(&rq->nr_iowait);
+}
+#endif
+
 void __sched io_schedule(void)
 {
 	struct rq *rq = raw_rq();
@@ -4218,14 +4233,7 @@ void __sched io_schedule(void)
 	current->in_iowait = 1;
 	schedule();
 	current->in_iowait = 0;
-#ifdef CONFIG_NO_HZ_COMMON
-	if (atomic_dec_and_test(&rq->nr_iowait)) {
-		if (raw_smp_processor_id() != cpu_of(rq))
-			tick_nohz_iowait_to_idle(cpu_of(rq));
-	}
-#else
-	atomic_dec(&rq->nr_iowait);
-#endif
+	io_wait_end(rq);
 	delayacct_blkio_end();
 }
 EXPORT_SYMBOL(io_schedule);
@@ -4241,14 +4249,7 @@ long __sched io_schedule_timeout(long timeout)
 	current->in_iowait = 1;
 	ret = schedule_timeout(timeout);
 	current->in_iowait = 0;
-#ifdef CONFIG_NO_HZ_COMMON
-	if (atomic_dec_and_test(&rq->nr_iowait)) {
-		if (raw_smp_processor_id() != cpu_of(rq))
-			tick_nohz_iowait_to_idle(cpu_of(rq));
-	}
-#else
-	atomic_dec(&rq->nr_iowait);
-#endif
+	io_wait_end(rq);
 	delayacct_blkio_end();
 	return ret;
 }
-- 
1.8.1.4

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