Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 20 Mar 2019 11:12:10 -0700
From:   "Paul E. McKenney" <paulmck@linux.ibm.com>
To:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:     linux-kernel@vger.kernel.org,
        Josh Triplett <josh@joshtriplett.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        Joel Fernandes <joel@joelfernandes.org>, tglx@linutronix.de,
        Mike Galbraith <efault@gmx.de>
Subject: Re: [PATCH v2] rcu: Allow to eliminate softirq processing from
 rcutree
Reply-To: paulmck@linux.ibm.com
References: <20190318022434.GE4102@linux.ibm.com>
 <20190319114419.qlsw3i5bmndoyvao@linutronix.de>
 <20190320113219.d6c3gouqbnsnl5nj@linutronix.de>
 <20190320152146.GH4102@linux.ibm.com>
 <20190320154440.GA16332@linux.ibm.com>
 <20190320160547.s5lbeahr2y4jlzwt@linutronix.de>
 <20190320161500.GK4102@linux.ibm.com>
 <20190320163532.mr32oi53iaueuizw@linutronix.de>
 <20190320173001.GM4102@linux.ibm.com>
 <20190320175952.yh6yfy64vaiurszw@linutronix.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20190320175952.yh6yfy64vaiurszw@linutronix.de>
User-Agent: Mutt/1.5.21 (2010-09-15)
Message-Id: <20190320181210.GO4102@linux.ibm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Mar 20, 2019 at 06:59:52PM +0100, Sebastian Andrzej Siewior wrote:
> On 2019-03-20 10:30:01 [-0700], Paul E. McKenney wrote:
> > On Wed, Mar 20, 2019 at 05:35:32PM +0100, Sebastian Andrzej Siewior wrote:
> > > On 2019-03-20 09:15:00 [-0700], Paul E. McKenney wrote:
> > > > I am considering making it a module_param() to avoid namespace pollution,
> > > > as it would become something like rcutree.nosoftirq.
> > > > 
> > > > Thoughts?
> > > 
> > > nope, perfect.
> > 
> > Please see below for an untested patch.  Thoughts?
> 
> > -	if (rcu_softirq_enabled) {
> > +	if (!nosoftirq) {
> >  		raise_softirq(RCU_SOFTIRQ);
> >  	} else {
> 
> This double negation looks weird. Can we flip the logic somehow?
> /me testing if it works…

We could name it something like "use_softirq" and initialize it to true.
I am OK either way.

							Thanx, Paul