[PATCH] rcu: update: make RCU_EXPEDITE_BOOT default
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: 2016-11-02 16:30:17
Also in:
lkml
Subsystem:
read-copy update (rcu), the rest · Maintainers:
"Paul E. McKenney", Frederic Weisbecker, Neeraj Upadhyay, Joel Fernandes, Josh Triplett, Boqun Feng, Uladzislau Rezki, Linus Torvalds
RCU_EXPEDITE_BOOT should speed up the boot process by enforcing synchronize_rcu_expedited() instead of synchronize_rcu() during the boot process. There should be no reason why one does not want this and there is no need worry about real time latency at this point. Therefore make it default. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- Checked on two boxes and synchronize_rcu() was invoked four times before it reached rcu_end_inkernel_boot() init/Kconfig | 13 ------------- kernel/rcu/update.c | 6 ++---- 2 files changed, 2 insertions(+), 17 deletions(-)
diff --git a/init/Kconfig b/init/Kconfig
index b6c9166d878a..fe51bd3bbc61 100644
--- a/init/Kconfig
+++ b/init/Kconfig@@ -771,19 +771,6 @@ config RCU_NOCB_CPU_ALL endchoice -config RCU_EXPEDITE_BOOT - bool - default n - help - This option enables expedited grace periods at boot time, - as if rcu_expedite_gp() had been invoked early in boot. - The corresponding rcu_unexpedite_gp() is invoked from - rcu_end_inkernel_boot(), which is intended to be invoked - at the end of the kernel-only boot sequence, just before - init is exec'ed. - - Accept the default if unsure. - endmenu # "RCU Subsystem" config BUILD_BIN2C
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index b40d3468ba4e..419ca811bda9 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c@@ -130,8 +130,7 @@ bool rcu_gp_is_normal(void) } EXPORT_SYMBOL_GPL(rcu_gp_is_normal); -static atomic_t rcu_expedited_nesting = - ATOMIC_INIT(IS_ENABLED(CONFIG_RCU_EXPEDITE_BOOT) ? 1 : 0); +static atomic_t rcu_expedited_nesting = ATOMIC_INIT(1); /* * Should normal grace-period primitives be expedited? Intended for
@@ -179,8 +178,7 @@ EXPORT_SYMBOL_GPL(rcu_unexpedite_gp); */ void rcu_end_inkernel_boot(void) { - if (IS_ENABLED(CONFIG_RCU_EXPEDITE_BOOT)) - rcu_unexpedite_gp(); + rcu_unexpedite_gp(); if (rcu_normal_after_boot) WRITE_ONCE(rcu_normal, 1); }
--
2.10.2