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From: Uladzislau Rezki <urezki@gmail.com>
Date: Fri, 8 Mar 2024 16:05:15 +0100
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Joel Fernandes <joel@joelfernandes.org>, linux-kernel@vger.kernel.org,
	frederic@kernel.org, boqun.feng@gmail.com, urezki@gmail.com,
	neeraj.iitr10@gmail.com, rcu@vger.kernel.org, rostedt@goodmis.org,
	Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
	Josh Triplett <josh@joshtriplett.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Zqiang <qiang.zhang1211@gmail.com>
Subject: Re: [PATCH] [RFC] rcu/tree: Reduce wake up for synchronize_rcu()
 common case
Message-ID: <ZespK0CrkVFCu6_p@pc636>
References: <20240307234852.2132637-1-joel@joelfernandes.org>
 <CAEXW_YQ-TZB-1gpxvf7v+QAZhHtzV5waBA1VemtgEwNktSp=ww@mail.gmail.com>
 <ccbdf4d4-6972-430c-a479-0d20b318213b@paulmck-laptop>
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On Thu, Mar 07, 2024 at 04:06:06PM -0800, Paul E. McKenney wrote:
> On Thu, Mar 07, 2024 at 06:52:14PM -0500, Joel Fernandes wrote:
> > On Thu, Mar 7, 2024 at 6:48 PM Joel Fernandes (Google)
> > <joel@joelfernandes.org> wrote:
> > >
> > > 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@joelfernandes.org>
> > > ---
> > 
> > Forgot to mention, this is based on the latest RCU -dev branch and
> > passes light rcutorture testing on all configs. Heavier rcutorture
> > testing (60 minutes) was performed on TREE03.
> 
> Very good, thank you!
> 
> Uladzislau, could you please pull this into the next series you send?
> I can then replace your commits in -rcu with the updated series.
> 
Absolutely. I will go through it and send out the next version!

--
Uladzislau Rezki