documentation: Fix relation between nohz_full and rcu_nocbs

If a CPU is specified in the nohz_full= kernel boot parameter to a
kernel built with CONFIG_NO_HZ_FULL=y, then that CPU's callbacks will
be offloaded, just as if that CPU had also been specified in the
rcu_nocbs= kernel boot parameter.  But the current documentation
states that the user must keep these two boot parameters manually
synchronized.  This commit therefore updates the documentation to
reflect reality.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index d9c171c..3a99cc9 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2633,9 +2633,10 @@
                        In kernels built with CONFIG_NO_HZ_FULL=y, set
                        the specified list of CPUs whose tick will be stopped
                        whenever possible. The boot CPU will be forced outside
-                       the range to maintain the timekeeping.
-                       The CPUs in this range must also be included in the
-                       rcu_nocbs= set.
+                       the range to maintain the timekeeping.  Any CPUs
+                       in this list will have their RCU callbacks offloaded,
+                       just as if they had also been called out in the
+                       rcu_nocbs= boot parameter.
 
        noiotrap        [SH] Disables trapped I/O port accesses.