From owner-freebsd-current@FreeBSD.ORG Sun Oct 30 14:30:41 2005 Return-Path: X-Original-To: freebsd-current@freebsd.org Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 7E13E16A41F; Sun, 30 Oct 2005 14:30:41 +0000 (GMT) (envelope-from scottl@samsco.org) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.FreeBSD.org (Postfix) with ESMTP id E675843D45; Sun, 30 Oct 2005 14:30:40 +0000 (GMT) (envelope-from scottl@samsco.org) Received: from [192.168.254.11] (junior.samsco.home [192.168.254.11]) (authenticated bits=0) by pooker.samsco.org (8.13.4/8.13.4) with ESMTP id j9UEUdAr049204; Sun, 30 Oct 2005 07:30:39 -0700 (MST) (envelope-from scottl@samsco.org) Message-ID: <4364D90F.3090205@samsco.org> Date: Sun, 30 Oct 2005 07:30:39 -0700 From: Scott Long User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.7.8) Gecko/20050615 X-Accept-Language: en-us, en MIME-Version: 1.0 To: freebsd-current@freebsd.org References: <30595.1130493297@critter.freebsd.dk> <20051028153457.d0wqgn2ask4sgw4k@netchild.homeip.net> <20051029195703.GB39253@dragon.NUXI.org> <43646AAC.2080107@freebsd.org> <20051030093718.GE39253@dragon.NUXI.org> In-Reply-To: <20051030093718.GE39253@dragon.NUXI.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-1.4 required=3.8 tests=ALL_TRUSTED autolearn=failed version=3.1.0 X-Spam-Checker-Version: SpamAssassin 3.1.0 (2005-09-13) on pooker.samsco.org Cc: Alexander Leidinger , David Xu Subject: Re: TSC instead of ACPI: powerd doesn't work anymore (to be expected?) X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 30 Oct 2005 14:30:41 -0000 David O'Brien wrote: > On Sun, Oct 30, 2005 at 02:39:40PM +0800, David Xu wrote: > >>David O'Brien wrote: >> >>>On Fri, Oct 28, 2005 at 03:34:57PM +0200, Alexander Leidinger wrote: >>> >>>>I don't have the message at hand. I just had time to write the mail, but I >>>>don't have my laptop with me to reproduce the message. But it's easy to >>>>reproduce, just take a PC which is able to make use of powerd and switch >>>>to >>>>using TSC as the timecounter. >>> >>>What is the motivation to use the TSC as a timecounter? >> >>TSC is faster than any others, on many systems, so-called ACPI-fast >>timer is really a slow chip, > > > Correct, but why is it felt the latency of the ACPI timer is an issue? > Of course we all want things to as fast as possible, but is that just an > abstract desire, or a real issue was run into? > ACPI-fast requires an ioport read which takes about 1us (according to Google). Do that 1000 times a second and you have each CPU spending 1% of its time doing nothing but reading the clock. Yikes. Scott