From owner-freebsd-current@FreeBSD.ORG Mon Oct 31 16:03:08 2005 Return-Path: X-Original-To: freebsd-current@FreeBSD.org Delivered-To: freebsd-current@FreeBSD.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 1E5C416A41F; Mon, 31 Oct 2005 16:03:08 +0000 (GMT) (envelope-from obrien@NUXI.com) Received: from dragon.NUXI.org (trang.nuxi.com [66.93.134.19]) by mx1.FreeBSD.org (Postfix) with ESMTP id A489843D45; Mon, 31 Oct 2005 16:03:07 +0000 (GMT) (envelope-from obrien@NUXI.com) Received: from dragon.NUXI.org (obrien@localhost [127.0.0.1]) by dragon.NUXI.org (8.13.4/8.13.4) with ESMTP id j9VG36P8020228; Mon, 31 Oct 2005 08:03:06 -0800 (PST) (envelope-from obrien@dragon.NUXI.org) Received: (from obrien@localhost) by dragon.NUXI.org (8.13.4/8.13.1/Submit) id j9VG35UZ020227; Mon, 31 Oct 2005 08:03:05 -0800 (PST) (envelope-from obrien) Date: Mon, 31 Oct 2005 08:03:05 -0800 From: "David O'Brien" To: Poul-Henning Kamp Message-ID: <20051031160305.GA20092@dragon.NUXI.org> Mail-Followup-To: obrien@freebsd.org, Poul-Henning Kamp , Robert Watson , Alexander Leidinger , freebsd-current@freebsd.org, David Xu References: <20051031102424.V11619@fledge.watson.org> <81484.1130756628@critter.freebsd.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <81484.1130756628@critter.freebsd.dk> X-Operating-System: FreeBSD 7.0-CURRENT Organization: The NUXI BSD Group X-Pgp-Rsa-Fingerprint: B7 4D 3E E9 11 39 5F A3 90 76 5D 69 58 D9 98 7A X-Pgp-Rsa-Keyid: 1024/34F9F9D5 User-Agent: Mutt/1.5.9i Cc: Alexander Leidinger , freebsd-current@FreeBSD.org, Robert Watson , David Xu Subject: Re: TSC instead of ACPI: powerd doesn't work anymore (to be expected?) X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: obrien@FreeBSD.org List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 31 Oct 2005 16:03:08 -0000 On Mon, Oct 31, 2005 at 12:03:48PM +0100, Poul-Henning Kamp wrote: > If somebody with access to the necessary docs (ie: Intel + AMD NDAs) > writes a piece of code that can tell us if using the TSC is safe, > then we can also use the TSC in those cases. There are cases where the TSC will count slower while the processor is HTL'ed on AMD64 CPU's. This can make TSC's get out of sync on dual core processors. There has been an on-going thread on the x86-64 mailing list on the issue affecting Linux. Linux developers assumed dual-core CPU's had a synced TSC between cores. Ensuring the use of the ACPI (PMTIMER) or HPET has been recommended. To help the situation, AMD has publicly announced the RDTSCP (read TSCP pair) instruction. Also that future AMD64 processors will have a P-state (power state) invariant TSC. -- -- David (obrien@FreeBSD.org)