linux-kernel - [PATCH v2 3/3] doc: Add rcutree.rcu_normal_wake_from

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Date:   Mon, 30 Oct 2023 14:12:54 +0100
From:   "Uladzislau Rezki (Sony)" <urezki@...il.com>
To:     "Paul E . McKenney" <paulmck@...nel.org>
Cc:     RCU <rcu@...r.kernel.org>,
        Neeraj upadhyay <Neeraj.Upadhyay@....com>,
        Boqun Feng <boqun.feng@...il.com>,
        Hillf Danton <hdanton@...a.com>,
        Joel Fernandes <joel@...lfernandes.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Uladzislau Rezki <urezki@...il.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>,
        Frederic Weisbecker <frederic@...nel.org>
Subject: [PATCH v2 3/3] doc: Add rcutree.rcu_normal_wake_from_gp to kernel-parameters.txt

This commit adds rcutree.rcu_normal_wake_from_gp description
to the kernel-parameters.txt file.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
---
 Documentation/admin-guide/kernel-parameters.txt | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 03a4bdb7512b..a9681d2492d3 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5009,6 +5009,20 @@
 			this kernel boot parameter, forcibly setting it
 			to zero.
 
+	rcutree.rcu_normal_wake_from_gp= [KNL]
+			Reduces a latency of synchronize_rcu() call. This approach
+			maintains its own track of synchronize_rcu() callers, so it
+			does not interact with regular callbacks because it does not
+			use a call_rcu[_hurry]() path. Please note, this is for a
+			normal grace period.
+
+			How to enable it:
+
+			echo 1 > /sys/module/rcutree/parameters/rcu_normal_wake_from_gp
+			or pass a boot parameter "rcutree.rcu_normal_wake_from_gp=1"
+
+			Default is 0.
+
 	rcuscale.gp_async= [KNL]
 			Measure performance of asynchronous
 			grace-period primitives such as call_rcu().
-- 
2.30.2