diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-08-04 17:31:12 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-08-19 17:18:04 -0700 |
| commit | 4d87ffadbba88105f33271bef5f2c79366c6a4e1 (patch) | |
| tree | b9866241327c17a810c3c9ca9bac0f525762cb7e /init | |
| parent | 910b1b7e19a292ff685001caf1bf1a9775b771a1 (diff) | |
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 <jkacur@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'init')
| -rw-r--r-- | init/Kconfig | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/init/Kconfig b/init/Kconfig index 79ac52bef4c..dbc08baad77 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -388,9 +388,12 @@ config RCU_FANOUT help 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. |