From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262175AbVFUQsJ (ORCPT ); Tue, 21 Jun 2005 12:48:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262203AbVFUQrw (ORCPT ); Tue, 21 Jun 2005 12:47:52 -0400 Received: from twilight.ucw.cz ([81.30.235.3]:48106 "EHLO suse.cz") by vger.kernel.org with ESMTP id S262171AbVFUQpL (ORCPT ); Tue, 21 Jun 2005 12:45:11 -0400 Date: Tue, 21 Jun 2005 18:45:19 +0200 From: Vojtech Pavlik To: Lee Revell Cc: Adam Goode , Pavel Machek , Alejandro Bonilla , linux-kernel@vger.kernel.org, linux-thinkpad@linux-thinkpad.org Subject: Re: IBM HDAPS Someone interested? Message-ID: <20050621164519.GA11601@ucw.cz> References: <20050620155720.GA22535@ucw.cz> <005401c575b3_5f5bba90_600cc60a@amer.sykes.com> <20050620163456.GA24111@ucw.cz> <20050620165703.GB477@openzaurus.ucw.cz> <20050620204533.GA9520@ucw.cz> <1119303016.5194.24.camel@lynx.auton.cs.cmu.edu> <1119368259.19357.18.camel@mindpipe> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1119368259.19357.18.camel@mindpipe> User-Agent: Mutt/1.5.6i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 21, 2005 at 11:37:38AM -0400, Lee Revell wrote: > On Mon, 2005-06-20 at 17:30 -0400, Adam Goode wrote: > > Freefall detection: 300 ms > > Head park time: 300-500 ms > > (from page 2 of document) > > > > Still doesn't seem too bad to figure out how to code though, at least > > once we can figure out how to get the data stream! > > > > P.S. The main control system runs as a Windows kernel driver. Not as > > safe as full hardware, but probably better than userspace. :) > > > > Ugh, if userspace can't meet a 300ms RT constraint, that's a pretty > shitty OS you have there. It's not that you do one measurement in the 300ms. You need to do at least 100, and some computations, too. > This should certainly be done in userspace on Linux. So it's a 3ms RT constraint, which is not as easy. -- Vojtech Pavlik SuSE Labs, SuSE CR