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Commit 4d87ffad authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Fix RCU_FANOUT help message 



Commit cf244dc0 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: default avatarJohn Kacur <jkacur@redhat.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 910b1b7e

init/Kconfig

+6 −3
Original line number Diff line number Diff line
@@ -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.