|author||Paul E. McKenney <email@example.com>||2010-08-04 17:31:12 -0700|
|committer||Paul E. McKenney <firstname.lastname@example.org>||2010-08-19 17:18:04 -0700|
rcu: Fix RCU_FANOUT help message
Commit cf244dc01bf68 added a fourth level to the TREE_RCU hierarchy, but the RCU_FANOUT help message still said "cube root". This commit fixes this to "fourth root" and also emphasizes that production systems are well-served by the default. (Stress-testing RCU itself uses small RCU_FANOUT values in order to test large-system code paths on small(er) systems.) Located-by: John Kacur <email@example.com> Signed-off-by: Paul E. McKenney <firstname.lastname@example.org>
1 files changed, 6 insertions, 3 deletions
diff --git a/init/Kconfig b/init/Kconfig
index 79ac52bef4c..dbc08baad77 100644
@@ -388,9 +388,12 @@ config RCU_FANOUT
This option controls the fanout of hierarchical implementations
of RCU, allowing RCU to work efficiently on machines with
- large numbers of CPUs. This value must be at least the cube
- root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
- systems and up to 262,144 for 64-bit systems.
+ large numbers of CPUs. This value must be at least the fourth
+ root of NR_CPUS, which allows NR_CPUS to be insanely large.
+ The default value of RCU_FANOUT should be used for production
+ systems, but if you are stress-testing the RCU implementation
+ itself, small RCU_FANOUT values allow you to test large-system
+ code paths on small(er) systems.
Select a specific number if testing RCU itself.
Take the default if unsure.