From owner-freebsd-questions@FreeBSD.ORG Wed Jan 28 06:10:05 2009 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id B65011065670 for ; Wed, 28 Jan 2009 06:10:05 +0000 (UTC) (envelope-from bruce@cran.org.uk) Received: from muon.cran.org.uk (brucec-1-pt.tunnel.tserv4.nyc4.ipv6.he.net [IPv6:2001:470:1f06:c09::2]) by mx1.freebsd.org (Postfix) with ESMTP id 7470E8FC23 for ; Wed, 28 Jan 2009 06:10:05 +0000 (UTC) (envelope-from bruce@cran.org.uk) Received: from muon.cran.org.uk (localhost [127.0.0.1]) by muon.cran.org.uk (Postfix) with ESMTP id E3EE81901D; Wed, 28 Jan 2009 01:10:03 -0500 (EST) X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on muon X-Spam-Level: X-Spam-Status: No, score=-2.5 required=8.0 tests=AWL,BAYES_00,NO_RELAYS autolearn=ham version=3.2.5 Received: from gluon (unknown [IPv6:2a01:348:10f:0:240:f4ff:fe57:9871]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by muon.cran.org.uk (Postfix) with ESMTPSA; Wed, 28 Jan 2009 01:10:03 -0500 (EST) Date: Wed, 28 Jan 2009 06:09:56 +0000 From: Bruce Cran To: Shawn Badger Message-ID: <20090128060956.0c164685@gluon> In-Reply-To: <497F9683.3080905@gmail.com> References: <497F9683.3080905@gmail.com> X-Mailer: Claws Mail 3.3.1 (GTK+ 2.12.9; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: freebsd-questions@freebsd.org Subject: Re: Laptop battery life on FreeBSD X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 28 Jan 2009 06:10:05 -0000 On Tue, 27 Jan 2009 16:19:31 -0700 Shawn Badger wrote: > Hi, I recently installed FreeBSD 7.1 on my laptop, replacing Arch > Linux and I noticed a significant drop in my battery life (from ~3 > hours to ~1.5 hours). I realize that Linux has their "tickless" > kernel, which I am sure explains the difference, but my question > is... is there anything I can do in FreeBSD right now to improve > this? And is there going to be any work done the kernel to allow the > hardware to enter into a low-power state for an extended period of > time? > > My laptop is an Acer Travelmate 4100 which has the following hardware: > - Pentium M 1.6 GHz processer > - 2 GB RAM > - integrated video/sound > - 802.11bg / bluetooth > > I'm somewhat of a minimalist and don't use X11. I've disabled the > bluetooth adapter, but frequently use my wireless adapter (intel > pro/2200bg). Does anyone have any suggestions that could potentially > extend my battery life? powerd isn't run by default, so the laptop will always be running at maximum frequency. By putting powerd_enable="YES" in /etc/rc.conf the CPU will throttle back whenever the system is idle. You can also tell FreeBSD to enter lower Cx states when idle by setting dev.cpu.x.cx_lowest, if it's supported. For example my VIA EPIA system has the following dev.cpu tree: > sysctl dev.cpu dev.cpu.0.%desc: ACPI CPU dev.cpu.0.%driver: cpu dev.cpu.0.%location: handle=\_PR_.CPU0 dev.cpu.0.%pnpinfo: _HID=none _UID=0 dev.cpu.0.%parent: acpi0 dev.cpu.0.freq: 533 dev.cpu.0.freq_levels: 533/-1 266/-1 dev.cpu.0.cx_supported: C1/0 C2/90 C3/900 dev.cpu.0.cx_lowest: C1 dev.cpu.0.cx_usage: 100.00% 0.00% 0.00% -- Bruce Cran