documentation: Update rcutree.kthread_prio for grace-period kthread use

Now that the rcutree.kthread_prio kernel boot parameter also controls
the priority of the grace-period kthreads, update the documentation to
reflect this change.

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

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index bfcb1a6..d913e3b 100644 (file)
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2991,11 +2991,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                        value is one, and maximum value is HZ.
 
        rcutree.kthread_prio=    [KNL,BOOT]
-                       Set the SCHED_FIFO priority of the RCU
-                       per-CPU kthreads (rcuc/N). This value is also
-                       used for the priority of the RCU boost threads
-                       (rcub/N). Valid values are 1-99 and the default
-                       is 1 (the least-favored priority).
+                       Set the SCHED_FIFO priority of the RCU per-CPU
+                       kthreads (rcuc/N). This value is also used for
+                       the priority of the RCU boost threads (rcub/N)
+                       and for the RCU grace-period kthreads (rcu_bh,
+                       rcu_preempt, and rcu_sched). If RCU_BOOST is
+                       set, valid values are 1-99 and the default is 1
+                       (the least-favored priority).  Otherwise, when
+                       RCU_BOOST is not set, valid values are 0-99 and
+                       the default is zero (non-realtime operation).
 
        rcutree.rcu_nocb_leader_stride= [KNL]
                        Set the number of NOCB kthread groups, which