linux-kernel - Re: [PATCH] [RFC] rcu/tree: Reduce wake up for synchronize

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Date: Fri, 8 Mar 2024 23:10:27 +0100
From: Frederic Weisbecker <frederic@...nel.org>
To: "Joel Fernandes (Google)" <joel@...lfernandes.org>
Cc: linux-kernel@...r.kernel.org, boqun.feng@...il.com, urezki@...il.com,
	neeraj.iitr10@...il.com, rcu@...r.kernel.org, rostedt@...dmis.org,
	"Paul E. McKenney" <paulmck@...nel.org>,
	Neeraj Upadhyay <neeraj.upadhyay@...nel.org>,
	Josh Triplett <josh@...htriplett.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Lai Jiangshan <jiangshanlai@...il.com>,
	Zqiang <qiang.zhang1211@...il.com>
Subject: Re: [PATCH] [RFC] rcu/tree: Reduce wake up for synchronize_rcu()
 common case

Le Thu, Mar 07, 2024 at 06:48:51PM -0500, Joel Fernandes (Google) a écrit :
> In the synchronize_rcu() common case, we will have less than
> SR_MAX_USERS_WAKE_FROM_GP number of users per GP. Waking up the kworker
> is pointless just to free the last injected wait head since at that point,
> all the users have already been awakened.
> 
> Introduce a new counter to track this and prevent the wakeup in the
> common case.
> 
> Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>

Reviewed-by: Frederic Weisbecker <frederic@...nel.org>