From owner-freebsd-questions@FreeBSD.ORG Thu May 5 08:43:32 2005 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id EA2BD16A4CE for ; Thu, 5 May 2005 08:43:32 +0000 (GMT) Received: from smtp11.wanadoo.fr (smtp11.wanadoo.fr [193.252.22.31]) by mx1.FreeBSD.org (Postfix) with ESMTP id A058B43D6D for ; Thu, 5 May 2005 08:43:32 +0000 (GMT) (envelope-from atkielski.anthony@wanadoo.fr) Received: from me-wanadoo.net (localhost [127.0.0.1]) by mwinf1112.wanadoo.fr (SMTP Server) with ESMTP id 0A4FF1C000C1 for ; Thu, 5 May 2005 10:43:31 +0200 (CEST) Received: from pix.atkielski.com (ASt-Lambert-111-2-1-3.w81-50.abo.wanadoo.fr [81.50.80.3]) by mwinf1112.wanadoo.fr (SMTP Server) with ESMTP id E0AF61C000BB for ; Thu, 5 May 2005 10:43:30 +0200 (CEST) X-ME-UUID: 20050505084330920.E0AF61C000BB@mwinf1112.wanadoo.fr Date: Thu, 5 May 2005 10:43:30 +0200 From: Anthony Atkielski X-Priority: 3 (Normal) Message-ID: <352039115.20050505104330@wanadoo.fr> To: freebsd-questions@freebsd.org In-Reply-To: <34d0f02f0868350c3c07570e3a73ceef@mac.com> References: <42792740.3040501@houston.rr.com> <34d0f02f0868350c3c07570e3a73ceef@mac.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Subject: Re: Clock running fast X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: freebsd-questions@freebsd.org List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 05 May 2005 08:43:33 -0000 Charles Swiger writes: > Try changing the kern.timecounter.hardware sysctl; you can look at the > available choices via: > > sysctl kern.timecounter.choice So what do the choices mean? How are they used? On one machine, I see TSC, ACPI-fast, i8254, and dummy as choices, and ACPI-fast is selected (this is a P4 machine). On the other, older machine (a 2-processor Pentium Pro), I see TSC, i8254, and dummy, and i8254 is selected. I presume that TSC is a real-time clock based on the processor TSC, and I presume also that i8254 is such a clock based on the classic i8254 timer, but what is dummy, and what is ACPI-fast? What are the pros and cons of selecting different choices? -- Anthony