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Subject[PATCH tip/core/rcu 1/6] documentation: Fix relation between nohz_full and rcu_nocbs
Date
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>
---
Documentation/admin-guide/kernel-parameters.txt | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index d9c171ce4190..3a99cc96b6b1 100644
--- 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.

--
2.5.2
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