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From: "Paul E. McKenney" <paulmck@kernel.org>
To: Hillf Danton <hdanton@sina.com>
Cc: linux-kernel@vger.kernel.org, rcu@vger.kernel.org,
	akpm@linux-foundation.org, linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH RFC tip/core/rcu] Add shrinker to shift to fast/inefficient GP mode
Date: Fri, 8 May 2020 07:47:16 -0700	[thread overview]
Message-ID: <20200508144716.GG2869@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <20200508133743.9356-1-hdanton@sina.com>

On Fri, May 08, 2020 at 09:37:43PM +0800, Hillf Danton wrote:
> 
> On Thu, 7 May 2020 08:49:10 Paul E. McKenney wrote:
> >  
> > > +static void rcu_mph_info(void *data)
> >
> > This pointer will always be &rcu_state, so why not ignore the pointer
> > and use "rcu_state" below?
> >
> Yes you're right.
> 
> > RCU grace periods are inherently global, so I don't know of any way
> > for RCU to focus on a given NUMA node.  All or nothing.
> 
> Or is it feasible to expose certain RCU thing to VM, say, with which kswapd
> can kick grace period every time the kthreads think it's needed? That way
> the work to gauge memory pressure can be off RCU's shoulders.

A pair of functions RCU provides is easy for me.  ;-)

							Thanx, Paul

> > But on the
> > other hand, speeding up RCU grace periods will also help specific
> > NUMA nodes, so I believe that it is all good.
> > 
> > > +{
> > > +	struct rcu_state *state = data;
> > > +
> > > +	WRITE_ONCE(state->mph_end, jiffies + HZ / 10);
> > > +	smp_store_release(&state->mph, true);
> > > +	rcu_force_quiescent_state();
> > > +}
> > > +
> > > +static struct mph_subscriber rcu_mph_subscriber = {
> > > +	.info = rcu_mph_info,
> > > +	.data = &rcu_state,
> > 
> > Then this ".data" entry can be omitted, correct?
> 
> Yes :)
> 
> Hillf
> 

      parent reply	other threads:[~2020-05-08 14:47 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-07  0:42 [PATCH RFC tip/core/rcu] Add shrinker to shift to fast/inefficient GP mode Paul E. McKenney
2020-05-07  0:55 ` Andrew Morton
2020-05-07  2:45   ` Paul E. McKenney
2020-05-07 17:00   ` Johannes Weiner
2020-05-07 17:09     ` Paul E. McKenney
2020-05-07 17:29       ` Paul E. McKenney
2020-05-07 18:31       ` Johannes Weiner
2020-05-07 19:09         ` Paul E. McKenney
2020-05-08  9:00           ` Konstantin Khlebnikov
2020-05-08 14:46             ` Paul E. McKenney
2020-05-09  8:54               ` Konstantin Khlebnikov
2020-05-09 16:09                 ` Paul E. McKenney
2020-05-13  1:32                   ` Dave Chinner
2020-05-13  3:18                     ` Paul E. McKenney
2020-05-13  4:35                       ` Konstantin Khlebnikov
2020-05-13 12:52                         ` Paul E. McKenney
2020-05-13  5:07                       ` Dave Chinner
2020-05-13 13:03                         ` Paul E. McKenney
     [not found] ` <20200507093647.11932-1-hdanton@sina.com>
2020-05-07 15:49   ` Paul E. McKenney
     [not found]   ` <20200508133743.9356-1-hdanton@sina.com>
2020-05-08 14:47     ` Paul E. McKenney [this message]

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