From owner-cvs-src@FreeBSD.ORG Sun Jan 29 06:12:37 2006 Return-Path: X-Original-To: cvs-src@FreeBSD.org Delivered-To: cvs-src@FreeBSD.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 724FA16A420; Sun, 29 Jan 2006 06:12:37 +0000 (GMT) (envelope-from nate@root.org) Received: from www.cryptography.com (li-22.members.linode.com [64.5.53.22]) by mx1.FreeBSD.org (Postfix) with ESMTP id 21BB843D45; Sun, 29 Jan 2006 06:12:37 +0000 (GMT) (envelope-from nate@root.org) Received: from [10.0.0.240] (ppp-71-139-114-10.dsl.snfc21.pacbell.net [71.139.114.10]) by www.cryptography.com (8.12.8/8.12.8) with ESMTP id k0T6CZD8024783 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Sat, 28 Jan 2006 22:12:36 -0800 Message-ID: <43DC5CE4.3070002@root.org> Date: Sat, 28 Jan 2006 22:12:52 -0800 From: Nate Lawson User-Agent: Mozilla Thunderbird 1.0.6 (Windows/20050716) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Kris Kennaway References: <200601290551.k0T5pwEC028440@repoman.freebsd.org> <20060129060654.GA47495@xor.obsecurity.org> In-Reply-To: <20060129060654.GA47495@xor.obsecurity.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: cvs-src@FreeBSD.org, Nate Lawson , src-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/etc/defaults rc.conf X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 29 Jan 2006 06:12:37 -0000 Kris Kennaway wrote: > On Sun, Jan 29, 2006 at 05:51:58AM +0000, Nate Lawson wrote: > >>njl 2006-01-29 05:51:58 UTC >> >> FreeBSD src repository >> >> Modified files: >> etc/defaults rc.conf >> Log: >> Enable the lowest Cx state by default. This will save power and we have >> had enough testing of acpi_cpu to know this is stable now. > > > On my desktop system (running RELENG_6 though), setting > hw.acpi.cpu.cx_lowest=C0 causes atrocious performance. Is it broken > in 6.x? Uh, C0 is not a real C-state. C1 is the lowest actual one (it's the HLT instruction on x86). What's probably happening is the idle thread is spinning instead of HLTing and the time to switch in your active thread is slow. This is from acpi(4): hw.acpi.cpu.cx_lowest Lowest Cx state to use for idling the CPU. A scheduling algo- rithm will select states between C1 and this setting as system load dictates. To enable ACPI CPU idling control, machdep.cpu_idle_hlt must be set to 1. So see if setting machdep.cpu_idle_hlt=0 causes the same problem. I'll also add a check to disallow setting it to C0 and tell the root user to use sysctl machdep.cpu_idle_hlt instead. -- Nate