From owner-freebsd-mobile@FreeBSD.ORG Tue Aug 17 21:39:03 2004 Return-Path: Delivered-To: freebsd-mobile@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id D174016A4CE; Tue, 17 Aug 2004 21:39:03 +0000 (GMT) Received: from postal2.es.net (postal2.es.net [198.128.3.206]) by mx1.FreeBSD.org (Postfix) with ESMTP id B665843D1F; Tue, 17 Aug 2004 21:39:03 +0000 (GMT) (envelope-from oberman@es.net) Received: from ptavv.es.net ([198.128.4.29]) by postal2.es.net (Postal Node 2) with ESMTP (SSL) id IBA74465; Tue, 17 Aug 2004 14:39:03 -0700 Received: from ptavv (localhost [127.0.0.1]) by ptavv.es.net (Tachyon Server) with ESMTP id 36ACD5D04; Tue, 17 Aug 2004 14:39:03 -0700 (PDT) To: Paulius Bulotas In-reply-to: Your message of "Tue, 17 Aug 2004 10:37:52 +0300." <20040817073752.GC675@devnull.lt> Date: Tue, 17 Aug 2004 14:39:03 -0700 From: "Kevin Oberman" Message-Id: <20040817213903.36ACD5D04@ptavv.es.net> cc: freebsd-current@freebsd.org cc: Colin Percival cc: freebsd-mobile@freebsd.org Subject: Re: Enhanced SpeedStep driver available X-BeenThere: freebsd-mobile@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Mobile computing with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 17 Aug 2004 21:39:04 -0000 > Date: Tue, 17 Aug 2004 10:37:52 +0300 > From: Paulius Bulotas > Sender: owner-freebsd-current@freebsd.org > > Hello, > > On 04 08 16, Colin Percival wrote: > > I've also put together a very simple control daemon which > > reads kern.cp_time every second and adjusts the cpu frequency > > based on the fraction of cpu time which is idle. This increases > > my laptop's battery life by around 40%. > > works with my T40 with Pentium M 1300MHz. Only I doubt it would increase > life on battery, since the lowest speed is 600MHz. And if I run on > battery all the time, it's always 600MHz. So, now it only raises speed > (which still is good, since it makes cpu intensive jobs run faster), but > how this could prolong battery life? In normal conditions on battery I > can work ~2 hours (and in Windows ~4, but I use them rarely). So now > probably less? Or this has to do something with voltage? Assuming that your T40 works like my T30, it runs at the clock speed selected at boot time. So, if you boot on battery, you run at a slow speed (1.2 GHz on my T30). If you plug into AC, you stay there. Conversely, it you boot on AC and switch to battery, your speed stays at the max (1.8 GHz on my T30). So, it I had Enhanced SpeedStep on my T30 (I don't), I could boot on battery and speed up the CPU when I get to my power supply and, more importantly, I can pull the plug while something is running and reduce CPU speed to keep my battery alive for a while. -- R. Kevin Oberman, Network Engineer Energy Sciences Network (ESnet) Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab) E-mail: oberman@es.net Phone: +1 510 486-8634