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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org
Cc: Ben Segall <bsegall@google.com>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Ingo Molnar <mingo@redhat.com>,
	Juri Lelli <juri.lelli@redhat.com>, Mel Gorman <mgorman@suse.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vincent Guittot <vincent.guittot@linaro.org>
Subject: [PATCH] sched: Make preempt_enable_no_resched() behave like preempt_enable() on PREEMPT_RT
Date: Tue, 1 Mar 2022 19:30:32 +0100	[thread overview]
Message-ID: <Yh5mSGCbvqDdeCa3@linutronix.de> (raw)

From: Thomas Gleixner <tglx@linutronix.de>

Use the distinction that has been made earlier between
preempt_enable_no_resched() and sched_preempt_enable_no_resched().
sched_preempt_enable_no_resched() is used within the scheduler where an
immediate schedule() follows. preempt_enable_no_resched() is used
outside of the scheduler and an immediate schedule() invocation may not
follow for other reasons.

The lack of an immediate schedule() invocation matters on PREEMPT_RT
where it will introduce latencies while the scheduler expects a context
switch.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 include/linux/preempt.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index b4381f255a5ca..582e43856a532 100644
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -210,7 +210,11 @@ do { \
 	preempt_count_dec(); \
 } while (0)
 
-#define preempt_enable_no_resched() sched_preempt_enable_no_resched()
+#ifdef CONFIG_PREEMPT_RT
+# define preempt_enable_no_resched() preempt_enable()
+#else
+# define preempt_enable_no_resched() sched_preempt_enable_no_resched()
+#endif
 
 #define preemptible()	(preempt_count() == 0 && !irqs_disabled())
 
-- 
2.35.1


             reply	other threads:[~2022-03-01 18:30 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-01 18:30 Sebastian Andrzej Siewior [this message]
2022-03-01 20:14 ` [PATCH] sched: Make preempt_enable_no_resched() behave like preempt_enable() on PREEMPT_RT Peter Zijlstra
2022-03-01 20:23   ` Sebastian Andrzej Siewior

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