From e6e0994ce5c645183058e28ff889447c644f8d97 Mon Sep 17 00:00:00 2001
Message-Id: <e6e0994ce5c645183058e28ff889447c644f8d97.1592846147.git.zanussi@kernel.org>
In-Reply-To: <07cd0dbc80b976663c80755496a03f288decfe5a.1592846146.git.zanussi@kernel.org>
References: <07cd0dbc80b976663c80755496a03f288decfe5a.1592846146.git.zanussi@kernel.org>
From: Julia Cartwright <julia@ni.com>
Date: Wed, 12 Oct 2016 11:21:14 -0500
Subject: [PATCH 163/330] rcu: enable rcu_normal_after_boot by default for RT
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.127-rt55.tar.xz

The forcing of an expedited grace period is an expensive and very
RT-application unfriendly operation, as it forcibly preempts all running
tasks on CPUs which are preventing the gp from expiring.

By default, as a policy decision, disable the expediting of grace
periods (after boot) on configurations which enable PREEMPT_RT_FULL.

Suggested-by: Luiz Capitulino <lcapitulino@redhat.com>
Acked-by: Paul E. McKenney <paulmck@linux.ibm.com>
Signed-off-by: Julia Cartwright <julia@ni.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 kernel/rcu/update.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 6ffafb1b1584..16d8dba23329 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -68,7 +68,7 @@ extern int rcu_expedited; /* from sysctl */
 module_param(rcu_expedited, int, 0);
 extern int rcu_normal; /* from sysctl */
 module_param(rcu_normal, int, 0);
-static int rcu_normal_after_boot;
+static int rcu_normal_after_boot = IS_ENABLED(CONFIG_PREEMPT_RT_FULL);
 module_param(rcu_normal_after_boot, int, 0);
 #endif /* #ifndef CONFIG_TINY_RCU */
 
-- 
2.17.1

