From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751460AbWGYSCB (ORCPT ); Tue, 25 Jul 2006 14:02:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751461AbWGYSCB (ORCPT ); Tue, 25 Jul 2006 14:02:01 -0400 Received: from alnrmhc14.comcast.net ([204.127.225.94]:2704 "EHLO alnrmhc11.comcast.net") by vger.kernel.org with ESMTP id S1751460AbWGYSCA (ORCPT ); Tue, 25 Jul 2006 14:02:00 -0400 Subject: Re: [PATCH] RTC: Add mmap method to rtc character driver From: Jim Gettys Reply-To: jg@laptop.org To: Arjan van de Ven Cc: Neil Horman , linux-kernel@vger.kernel.org, a.zummo@towertech.it, jg@freedesktop.org, Keith Packard In-Reply-To: <1153850139.8932.40.camel@laptopd505.fenrus.org> References: <20060725174100.GA4608@hmsreliant.homelinux.net> <1153850139.8932.40.camel@laptopd505.fenrus.org> Content-Type: text/plain Organization: OLPC Date: Tue, 25 Jul 2006 14:01:54 -0400 Message-Id: <1153850514.5872.107.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2006-07-25 at 19:55 +0200, Arjan van de Ven wrote: > > @@ -265,6 +269,7 @@ irqreturn_t rtc_interrupt(int irq, void > > > > kill_fasync (&rtc_async_queue, SIGIO, POLL_IN); > > > > + *count_ptr = (*count_ptr)++; > > Hi, > > it's a cute idea, however 3 questions: > 1) you probably want to add a few memory barriers around this, right? > 2) why use the rtc and not the regular timer interrupt? > > (and > 3) this will negate the power gain you get for tickless kernels, since > now they need to start ticking again ;( ) The field only needs to get updated if you've scheduled something to run... - Jim > > Greetings, > Arjan van de Ven > -- Jim Gettys One Laptop Per Child