rcu: update: Make RCU_EXPEDITE_BOOT be the default
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.
Note that users wishing to avoid expediting entirely, for example when
bringing up new hardware possibly having flaky IPIs, can use the
rcu_normal boot parameter to override boot-time expediting.
Change-Id: I758bb7819bb2b18ad7232c3e943b9c1cb85d49e9
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
[ paulmck: Reworded commit log. ]
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
diff --git a/init/Kconfig b/init/Kconfig
index 007186d..2c382dc1 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -795,19 +795,6 @@
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 4f6db7e..9e03db9 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -132,8 +132,7 @@
}
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
@@ -182,8 +181,7 @@
*/
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);
}