rcu: Clarify RCU_LAZY and RCU_LAZY_DEFAULT_OFF help text

This commit wordsmiths the RCU_LAZY and RCU_LAZY_DEFAULT_OFF Kconfig
options' help text.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>

diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig
index b9b6bc55185dba365236b4f01d8aaa3596f70ecd..2bb22dac3b5a9a1dd7f66a132a9cb2f9884c8f4b 100644 (file)
--- a/kernel/rcu/Kconfig
+++ b/kernel/rcu/Kconfig
@@ -323,21 +323,27 @@ config RCU_LAZY
        depends on RCU_NOCB_CPU
        default n
        help
-         To save power, batch RCU callbacks and flush after delay, memory
-         pressure, or callback list growing too big.
+         To save power, batch RCU callbacks and delay starting the
+         corresponding grace  period for multiple seconds.  The grace
+         period will be started after this delay, in case of memory
+         pressure, or if the corresponding CPU's callback list grows
+         too large.
 
-         Requires rcu_nocbs=all to be set.
+         These delays happen only on rcu_nocbs CPUs, that is, CPUs
+         whose callbacks have been offloaded.
 
-         Use rcutree.enable_rcu_lazy=0 to turn it off at boot time.
+         Use the rcutree.enable_rcu_lazy=0 kernel-boot parameter to
+         globally disable these delays.
 
 config RCU_LAZY_DEFAULT_OFF
        bool "Turn RCU lazy invocation off by default"
        depends on RCU_LAZY
        default n
        help
-         Allows building the kernel with CONFIG_RCU_LAZY=y yet keep it default
-         off. Boot time param rcutree.enable_rcu_lazy=1 can be used to switch
-         it back on.
+         Build the kernel with CONFIG_RCU_LAZY=y, but cause the kernel
+         to boot with these energy-efficiency delays disabled.  Use the
+         rcutree.enable_rcu_lazy=0 kernel-boot parameter to override
+         the this option at boot time, thus re-enabling these delays.
 
 config RCU_DOUBLE_CHECK_CB_TIME
        bool "RCU callback-batch backup time check"