rcu: Fix RCU_FANOUT help message (4d87ffad) · Commits · 戴 / test

Commit 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>

init/Kconfig

+6 −3

Original line number	Original line	Diff line number	Diff line
	@@ -388,9 +388,12 @@ config RCU_FANOUT
	help		help
	This option controls the fanout of hierarchical implementations		This option controls the fanout of hierarchical implementations
	of RCU, allowing RCU to work efficiently on machines with		of RCU, allowing RCU to work efficiently on machines with
	large numbers of CPUs. This value must be at least the cube		large numbers of CPUs. This value must be at least the fourth
	root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit		root of NR_CPUS, which allows NR_CPUS to be insanely large.
	systems and up to 262,144 for 64-bit systems.		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.		Select a specific number if testing RCU itself.
	Take the default if unsure.		Take the default if unsure.

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