From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932503AbWGYW3i (ORCPT ); Tue, 25 Jul 2006 18:29:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932498AbWGYW3i (ORCPT ); Tue, 25 Jul 2006 18:29:38 -0400 Received: from ra.tuxdriver.com ([70.61.120.52]:35339 "EHLO ra.tuxdriver.com") by vger.kernel.org with ESMTP id S932503AbWGYW3g (ORCPT ); Tue, 25 Jul 2006 18:29:36 -0400 Date: Tue, 25 Jul 2006 18:25:47 -0400 From: Neil Horman To: "H. Peter Anvin" Cc: Dave Airlie , Segher Boessenkool , linux-kernel@vger.kernel.org, a.zummo@towertech.it, jg@freedesktop.org Subject: Re: [PATCH] RTC: Add mmap method to rtc character driver Message-ID: <20060725222547.GA3973@localhost.localdomain> References: <03BCDC7F-13D9-42FC-86FC-30C76FD3B3B8@kernel.crashing.org> <20060725182833.GE4608@hmsreliant.homelinux.net> <44C66C91.8090700@zytor.com> <20060725192138.GI4608@hmsreliant.homelinux.net> <20060725194733.GJ4608@hmsreliant.homelinux.net> <21d7e9970607251304n5681bf44gc751c21fd79be99d@mail.gmail.com> <44C67E1A.7050105@zytor.com> <20060725204736.GK4608@hmsreliant.homelinux.net> <44C6842C.8020501@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <44C6842C.8020501@zytor.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 25, 2006 at 01:50:52PM -0700, H. Peter Anvin wrote: > Neil Horman wrote: > > > >Agreed. How about we take the /dev/rtc patch now (since its an added > >feature > >that doesn't hurt anything if its not used, as far as tickless kernels > >go), and > >I'll start working on doing gettimeofday in vdso for arches other than > >x86_64. > >That will give the X guys what they wanted until such time until all the > >other > >arches have a gettimeofday alternative that doesn't require kernel traps. > > > > It hurts if it DOES get used. > Yes, but if its in trade for something thats being used currently which hurts more (case in point being the X server), using this solution is a net gain. I'm not arguing with you that adding a low res gettimeofday vsyscall is a better long term solution, but doing that requires potentially several implementations in the C library accross a range of architectures, some of which may not be able to provide a time solution any better than what the gettimeofday syscall provides today. The /dev/rtc solution is easy, available right now, and applies to all arches. It has zero impact for systems which do not use it, and for those applications which make a decision to use it instead of an alternate method, the result I expect will be a net gain, until such time as we code up, test and roll out a vsyscall solution Thanks & Regards Neil > -hpa