From: Arjan van de Ven <arjan@infradead.org>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: linux-input@vger.kernel.org, dipankar@in.ibm.com,
linux-kernel@vger.kernel.org
Subject: Re: Question about usage of RCU in the input layer
Date: Thu, 19 Mar 2009 07:02:21 -0700 [thread overview]
Message-ID: <20090319070221.6aca7245@infradead.org> (raw)
In-Reply-To: <200903190023.56929.dmitry.torokhov@gmail.com>
On Thu, 19 Mar 2009 00:23:56 -0700
Dmitry Torokhov <dmitry.torokhov@gmail.com> wrote:
> Hi Arjan,
>
> On Wednesday 18 March 2009 21:58:12 Arjan van de Ven wrote:
> > Hi,
> >
> > the input layer does a "synchronize_rcu()" after a
> > list_add_tail_rcu(), which is costing me 1 second of boot time.....
> > And based on my understanding of the RCU concept, you only need to
> > synchronize on delete, not on addition... so I think the
> > synchronize is entirely redundant here...
>
>
> It is there to guarantee that once we registered the handle all
> subsequent input events will be delivered through it.
afaik rcu already guarantees that even without a synchronize;
the only reason you would need a synchronize is to guarantee that
people STOPPED using your memory. Or am I now totally misunderstanding
RCU ?
next prev parent reply other threads:[~2009-03-19 14:01 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-19 4:58 Question about usage of RCU in the input layer Arjan van de Ven
2009-03-19 7:23 ` Dmitry Torokhov
2009-03-19 14:02 ` Arjan van de Ven [this message]
2009-03-19 8:56 ` Dipankar Sarma
2009-03-19 14:18 ` Arjan van de Ven
2009-03-20 2:07 ` Paul E. McKenney
2009-03-20 3:20 ` Arjan van de Ven
2009-03-20 4:45 ` Paul E. McKenney
2009-03-20 5:28 ` Eric Dumazet
2009-03-20 6:01 ` Dipankar Sarma
2009-03-20 6:35 ` Eric Dumazet
2009-03-20 13:50 ` Arjan van de Ven
2009-03-20 14:31 ` Paul E. McKenney
2009-03-20 18:13 ` Arjan van de Ven
2009-03-21 1:27 ` Paul E. McKenney
2009-03-21 4:58 ` Arjan van de Ven
2009-03-21 18:58 ` Paul E. McKenney
2009-03-21 19:51 ` Arjan van de Ven
2009-03-21 20:26 ` Eric Dumazet
2009-03-21 21:07 ` Paul E. McKenney
2009-03-22 3:40 ` Arjan van de Ven
2009-03-22 4:38 ` Paul E. McKenney
2009-03-22 4:51 ` Arjan van de Ven
2009-03-22 5:18 ` Paul E. McKenney
2009-03-22 5:53 ` Arjan van de Ven
2009-03-22 16:53 ` Paul E. McKenney
2009-03-22 19:46 ` Arjan van de Ven
2009-03-22 20:52 ` Paul E. McKenney
2009-03-22 22:44 ` Arjan van de Ven
2009-03-22 23:03 ` Paul E. McKenney
2009-03-22 23:16 ` Arjan van de Ven
2009-03-23 1:27 ` Paul E. McKenney
2009-04-03 1:27 ` Paul E. McKenney
2009-03-21 21:13 ` Arjan van de Ven
2009-03-20 22:21 ` Paul E. McKenney
2009-03-21 5:46 ` Dmitry Torokhov
2009-03-21 9:13 ` Eric Dumazet
2009-03-21 18:58 ` Paul E. McKenney
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