Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268641AbUIGVsG (ORCPT ); Tue, 7 Sep 2004 17:48:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268684AbUIGVrZ (ORCPT ); Tue, 7 Sep 2004 17:47:25 -0400 Received: from gateway-1237.mvista.com ([12.44.186.158]:3580 "EHLO av.mvista.com") by vger.kernel.org with ESMTP id S268685AbUIGVou (ORCPT ); Tue, 7 Sep 2004 17:44:50 -0400 Message-ID: <413E2B2E.3000706@mvista.com> Date: Tue, 07 Sep 2004 14:42:06 -0700 From: George Anzinger Reply-To: george@mvista.com Organization: MontaVista Software User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2.1) Gecko/20030225 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Christoph Lameter CC: Andi Kleen , john stultz , lkml , tim@physik3.uni-rostock.de, albert@users.sourceforge.net, Ulrich.Windl@rz.uni-regensburg.de, Len Brown , linux@dominikbrodowski.de, David Mosberger , paulus@samba.org, schwidefsky@de.ibm.com, jimix@us.ibm.com, keith maanthey , greg kh , Patricia Gaughen , Chris McDermott Subject: Re: [RFC] New Time of day proposal (updated 9/2/04) References: <1094159238.14662.318.camel@cog.beaverton.ibm.com> <20040903151710.GB12956@wotan.suse.de> <1094242317.14662.556.camel@cog.beaverton.ibm.com> <20040904130022.GB21912@wotan.suse.de> <413DFCC2.7080405@mvista.com> In-Reply-To: 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: 1299 Lines: 31 Christoph Lameter wrote: > On Tue, 7 Sep 2004, George Anzinger wrote: > > >>Also, we don't "know" what rate the TSC is actually clocking so we must >>"discover" it at boot time. This process either is inaccurate or slow (I think >>we use ~ 50 ms these days which gives an error of ~10 TSC cycles on a 800MHZ >>box). FWIW the problem here is the sync up with the I/O backplane to find the >>start and ending of the measured time. >> >>I suspect that the IA64 "tells" you what its clock rate is. Right? > > > Not the CPU itself. There is a special hardware I/O interface called the > PAL/SAL that allows one to retrieve that information. Doesn't the BIOS on > i386 allow you to get to that information? Not as far as I know. If it did we would kick out the calibrate loop and boot some 50ms faster (always a good thing). Could be somebody else has better info here... -- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml - 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/