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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ZespK0CrkVFCu6_p@pc636>
Date: Fri, 8 Mar 2024 16:05:15 +0100
From: Uladzislau Rezki <urezki@...il.com>
To: "Paul E. McKenney" <paulmck@...nel.org>
Cc: Joel Fernandes <joel@...lfernandes.org>, linux-kernel@...r.kernel.org,
	frederic@...nel.org, boqun.feng@...il.com, urezki@...il.com,
	neeraj.iitr10@...il.com, rcu@...r.kernel.org, rostedt@...dmis.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

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@...lfernandes.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@...lfernandes.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