linux-kernel - [PATCH tip/core/rcu 10/11] rcu/nocb: Rename rcu_nocb_leader

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Message-Id: <20190801225028.18225-10-paulmck@linux.ibm.com>
Date:   Thu,  1 Aug 2019 15:50:27 -0700
From:   "Paul E. McKenney" <paulmck@...ux.ibm.com>
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, mingo@...nel.org,
        jiangshanlai@...il.com, dipankar@...ibm.com,
        akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
        josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
        rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
        fweisbec@...il.com, oleg@...hat.com, joel@...lfernandes.org,
        "Paul E. McKenney" <paulmck@...ux.ibm.com>
Subject: [PATCH tip/core/rcu 10/11] rcu/nocb: Rename rcu_nocb_leader_stride kernel boot parameter

This commit changes the name of the rcu_nocb_leader_stride kernel
boot parameter to rcu_nocb_gp_stride in order to account for the new
distinction between callback and grace-period no-CBs kthreads.

Signed-off-by: Paul E. McKenney <paulmck@...ux.ibm.com>
---
 Documentation/admin-guide/kernel-parameters.txt | 13 +++++++------
 kernel/rcu/tree_plugin.h                        |  8 ++++----
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index f3fcd6140ee1..79b983bedcaa 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3837,12 +3837,13 @@
 			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
-			defaults to the square root of the number of
-			CPUs.  Larger numbers reduces the wakeup overhead
-			on the per-CPU grace-period kthreads, but increases
-			that same overhead on each group's leader.
+	rcutree.rcu_nocb_gp_stride= [KNL]
+			Set the number of NOCB callback kthreads in
+			each group, which defaults to the square root
+			of the number of CPUs.	Larger numbers reduce
+			the wakeup overhead on the global grace-period
+			kthread, but increases that same overhead on
+			each group's NOCB grace-period kthread.
 
 	rcutree.qhimark= [KNL]
 			Set threshold of queued RCU callbacks beyond which
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index be065aacd63b..80b27a9f306d 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -2126,8 +2126,8 @@ static void __init rcu_spawn_nocb_kthreads(void)
 }
 
 /* How many CB CPU IDs per GP kthread?  Default of -1 for sqrt(nr_cpu_ids). */
-static int rcu_nocb_leader_stride = -1;
-module_param(rcu_nocb_leader_stride, int, 0444);
+static int rcu_nocb_gp_stride = -1;
+module_param(rcu_nocb_gp_stride, int, 0444);
 
 /*
  * Initialize GP-CB relationships for all no-CBs CPU.
@@ -2135,7 +2135,7 @@ module_param(rcu_nocb_leader_stride, int, 0444);
 static void __init rcu_organize_nocb_kthreads(void)
 {
 	int cpu;
-	int ls = rcu_nocb_leader_stride;
+	int ls = rcu_nocb_gp_stride;
 	int nl = 0;  /* Next GP kthread. */
 	struct rcu_data *rdp;
 	struct rcu_data *rdp_gp = NULL;  /* Suppress misguided gcc warn. */
@@ -2145,7 +2145,7 @@ static void __init rcu_organize_nocb_kthreads(void)
 		return;
 	if (ls == -1) {
 		ls = int_sqrt(nr_cpu_ids);
-		rcu_nocb_leader_stride = ls;
+		rcu_nocb_gp_stride = ls;
 	}
 
 	/*
-- 
2.17.1