rcu: Update RCU_FAST_NO_HZ help text
The RCU_FAST_NO_HZ help text included a warning about overhead on large
systems, but that issue has since been resolved. The main remaining
issue with RCU_FAST_NO_HZ is increased real-time latency. This commit
therefore updates the help text accordingly.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/init/Kconfig b/init/Kconfig
index 6fdd6e3..b63e798 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -582,14 +582,13 @@
depends on NO_HZ && SMP
default n
help
- This option causes RCU to attempt to accelerate grace periods
- in order to allow CPUs to enter dynticks-idle state more
- quickly. On the other hand, this option increases the overhead
- of the dynticks-idle checking, particularly on systems with
- large numbers of CPUs.
+ This option causes RCU to attempt to accelerate grace periods in
+ order to allow CPUs to enter dynticks-idle state more quickly.
+ On the other hand, this option increases the overhead of the
+ dynticks-idle checking, thus degrading scheduling latency.
- Say Y if energy efficiency is critically important, particularly
- if you have relatively few CPUs.
+ Say Y if energy efficiency is critically important, and you don't
+ care about real-time response.
Say N if you are unsure.