From owner-freebsd-net@FreeBSD.ORG Tue Nov 8 16:11:09 2005 Return-Path: X-Original-To: freebsd-net@freebsd.org Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 4389516A420; Tue, 8 Nov 2005 16:11:09 +0000 (GMT) (envelope-from jhb@freebsd.org) Received: from speedfactory.net (mail5.speedfactory.net [66.23.216.218]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3A41143D53; Tue, 8 Nov 2005 16:10:59 +0000 (GMT) (envelope-from jhb@freebsd.org) Received: from server.baldwin.cx (unverified [66.23.211.162]) by speedfactory.net (SurgeMail 3.5b3) with ESMTP id 1586401 for multiple; Tue, 08 Nov 2005 11:13:00 -0500 Received: from localhost (john@localhost [127.0.0.1]) by server.baldwin.cx (8.13.1/8.13.1) with ESMTP id jA8GAjf5027042; Tue, 8 Nov 2005 11:10:52 -0500 (EST) (envelope-from jhb@freebsd.org) From: John Baldwin To: Vaibhave Agarwal Date: Tue, 8 Nov 2005 10:18:51 -0500 User-Agent: KMail/1.8.2 References: <20051027233636.GA39380@dmw.hopto.org> <200511071105.58729.jhb@freebsd.org> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200511081018.53452.jhb@freebsd.org> X-Spam-Status: No, score=-2.8 required=4.2 tests=ALL_TRUSTED autolearn=failed version=3.0.2 X-Spam-Checker-Version: SpamAssassin 3.0.2 (2004-11-16) on server.baldwin.cx X-Server: High Performance Mail Server - http://surgemail.com r=1653887525 Cc: freebsd-net@freebsd.org, freebsd-acpi@freebsd.org, current@freebsd.org, Nate Lawson Subject: Re: Freebsd 6.0 doesnt detect local APIC on a Pentium 3 machine X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 08 Nov 2005 16:11:09 -0000 On Monday 07 November 2005 08:38 pm, Vaibhave Agarwal wrote: > On Mon, 7 Nov 2005, John Baldwin wrote: > > And even then it can't be used for any device interrupts since there > > aren't any I/O APICs. On a UP machine without I/O APICs, it's actually > > probably more optimal to just use irq0 and irq8 for clocks rather than > > the lapic timer anyway. The only real possible gain is the ability to > > use the profiling interrupt from the local APIC. > > I got access to the BIOS of the Pentium 3 machine I am using, but it has > no option to enable/disable the local APIC. Yes, I've not seen any BIOSen that do. > Joseph Koshy is right, Linux enables the local APIC timer while booting > up. I got the following in the bootup log of Linux 2.4 kernel on the same > machine. > > ------------------------- > Local APIC disabled by BIOS -- reenabling. > Found and enabled local APIC! > > Using local APIC timer interrupts. > calibrating APIC timer ... > ------------------------- Just because Linux does for UP doesn't mean it is more optimal for FreeBSD. :) On FreeBSD with the lapic timer you have 2 * hz interrupts per second. With the irq0/irq8 combo you have hz + stathz interrupts per second. The difference is 2000 vs 1128. Granted, the lapic timer interrupt handler doesn't have to talk to hardware out on the LPC bus.. > Though there is no I/O apic in the UP machines, but I only wanted to use > local APIC timer in the lapic_timer_oneshot() mode to schedule few timers > accurately. You can increase the rate of the rtc timer. We run it at profhz (1024) when profiling is enabled for example. -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org