From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753003Ab0EVDh3 (ORCPT ); Fri, 21 May 2010 23:37:29 -0400 Received: from terminus.zytor.com ([198.137.202.10]:38281 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751931Ab0EVDh1 (ORCPT ); Fri, 21 May 2010 23:37:27 -0400 Message-ID: <4BF7507F.20805@zytor.com> Date: Fri, 21 May 2010 20:33:19 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100430 Fedora/3.0.4-2.fc12 Thunderbird/3.0.4 MIME-Version: 1.0 To: john stultz CC: Brian Bloniarz , Ingo Molnar , Thomas Gleixner , Peter Zijlstra , Andi Kleen , Dan Magenheimer , Arjan van de Ven , Venkatesh Pallipadi , chris.mason@oracle.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86: Export tsc related information in sysfs References: <4BF58B59.7080901@athenacr.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/21/2010 07:03 PM, john stultz wrote: > > Yea, the relative instability of the tsc calibration at boot is an > issue for folks who want very very precise timekeeping immediately > after a reboot. > > I proposed a solution to this awhile back via a boot option users > could use to specify the tsc_khz freq, so it would be consistent from > boot to boot. See: https://patchwork.kernel.org/patch/22492/ > > It didn't really go anywhere due to a lack of public interest. > However, if you're interested in playing with it, I can try to revive > the patch. > The point about NTP is a very good one; with NTP you *really* want what you're adjusting to be directly related to the crystal oscillator -- as what it is; precision over accuracy as NTP takes care of accuracy but not precision. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.