Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932217AbVKOAim (ORCPT ); Mon, 14 Nov 2005 19:38:42 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932219AbVKOAim (ORCPT ); Mon, 14 Nov 2005 19:38:42 -0500 Received: from gw02.applegatebroadband.net ([207.55.227.2]:8427 "EHLO data.mvista.com") by vger.kernel.org with ESMTP id S932217AbVKOAil (ORCPT ); Mon, 14 Nov 2005 19:38:41 -0500 Message-ID: <43792DFF.1000300@mvista.com> Date: Mon, 14 Nov 2005 16:38:23 -0800 From: George Anzinger Reply-To: george@mvista.com Organization: MontaVista Software User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20050922 Fedora/1.7.12-1.3.1 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Vojtech Pavlik CC: Andi Kleen , Jan Beulich , linux-kernel@vger.kernel.org, discuss@x86-64.org Subject: Re: [PATCH 13/39] NLKD/x86-64 - time adjustment References: <43720DAE.76F0.0078.0@novell.com> <200511110312.15616.ak@suse.de> <20051112092200.GA7997@midnight.suse.cz> <200511121821.11552.ak@suse.de> <20051112204428.GA14733@midnight.suse.cz> In-Reply-To: <20051112204428.GA14733@midnight.suse.cz> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1351 Lines: 38 Vojtech Pavlik wrote: > On Sat, Nov 12, 2005 at 06:21:11PM +0100, Andi Kleen wrote: > >>On Saturday 12 November 2005 10:22, Vojtech Pavlik wrote: >> >> >>>Is there any advantage to using 64-bit HPET? >> >>Yes - it can tolerate long delays between ticks, e.g. caused by noidletick / >>debuggers / target probes / smm etc. At least the first case will be fairly >>important soon. > > > A 32-bit 14 MHz HPET counter will overflow in approximately 5 minutes. I > don't think going 64-bit makes sense for noidletick, but for debuggers, > etc, it could make a good sense indeed. > > >>>It's read is even slower >> >>Why? The read should be on cache line granuality and there shouldn't >>be any difference in theory. > > > I'll try to measure this. Indeed, in theory there shouldn't be a > significant difference. > Doesn't this depend on the atomic nature of the 64-bit read? If it is really two 32-bit reads one would need to do extra work to make sure the two parts belong together. -- George Anzinger george@mvista.com HRT (High-res-timers): http://sourceforge.net/projects/high-res-timers/ - 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/