Date: Sun, 22 Mar 2009 13:52:12 -0700
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Eric Dumazet <dada1@cosmosbay.com>, dipankar@in.ibm.com,
       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
Message-ID: <20090322205212.GI7148@linux.vnet.ibm.com>
Reply-To: paulmck@linux.vnet.ibm.com
References: <20090321125115.0a76ac27@infradead.org> <49C54D60.80306@cosmosbay.com> <20090321210745.GE7148@linux.vnet.ibm.com> <20090321204045.4a9022fd@infradead.org> <20090322043838.GF7148@linux.vnet.ibm.com> <20090321215109.717a3f12@infradead.org> <20090322051822.GG7148@linux.vnet.ibm.com> <20090321225318.5b25f0a7@infradead.org> <20090322165324.GH7148@linux.vnet.ibm.com> <20090322124632.5d5d6266@infradead.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20090322124632.5d5d6266@infradead.org>
User-Agent: Mutt/1.5.15+20070412 (2007-04-11)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 857
Lines: 23

On Sun, Mar 22, 2009 at 12:46:32PM -0700, Arjan van de Ven wrote:
> On Sun, 22 Mar 2009 09:53:24 -0700
> "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote:
> 
> > > > How many synchronize_rcu() calls are you seeing on the boot path?
> > > 
> > > I see 20 that hit the above code path (eg ones that wait) until
> > > userspace starts.
> > 
> > So with well-behaved readers, the full sequence would be worth
> > something like 50-60 milliseconds.
> 
> yeah it's about 10% if the total kernel boot time.. so it does start to
> matter

Half-second boot, eh?  That would indeed be impressive.

							Thanx, Paul
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/