From: Dipankar Sarma <dipankar@in.ibm.com>
To: Arjan van de Ven <arjan@infradead.org>
Cc: linux-input@vger.kernel.org, dmitry.torokhov@gmail.com,
linux-kernel@vger.kernel.org
Subject: Re: Question about usage of RCU in the input layer
Date: Thu, 19 Mar 2009 14:26:28 +0530 [thread overview]
Message-ID: <20090319085628.GA6167@in.ibm.com> (raw)
In-Reply-To: <20090318215812.15496a86@infradead.org>
On Wed, Mar 18, 2009 at 09:58:12PM -0700, 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...
>
The more appropriate question is - why is synchronize_rcu() taking
1 second ? Any idea what the other CPUs are doing at the time
of calling synchronize_rcu() ? What driver is this ? How early
in the boot is this happening ?
Thanks
Dipankar
next prev parent reply other threads:[~2009-03-19 8:56 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
2009-03-19 8:56 ` Dipankar Sarma [this message]
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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