Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!cbosgd!ihnp4!cuuxb!mmengel From: mmengel@cuuxb.UUCP Newsgroups: comp.arch Subject: Re: Single tasking the wave of the future? Message-ID: <1423@cuuxb.ATT.COM> Date: Mon, 7-Dec-87 10:47:11 EST Article-I.D.: cuuxb.1423 Posted: Mon Dec 7 10:47:11 1987 Date-Received: Sat, 12-Dec-87 16:59:36 EST References: <201@PT.CS.CMU.EDU> <388@sdcjove.CAM.UNISYS.COM> <988@edge.UUCP> <1227@sugar.UUCP> <151@sdeggo.UUCP> Reply-To: mmengel@cuuxb.UUCP (Marc W. Mengel) Organization: AT&T-DSD, System Engineering for Resellers, Lisle IL Lines: 41 In article <151@sdeggo.UUCP> dave@sdeggo.UUCP (David L. Smith) writes: $In article <1227@sugar.UUCP>, peter@sugar.UUCP (Peter da Silva) writes: $ >In article <147@sdeggo.UUCP>, dave@sdeggo.UUCP (David L. Smith) writes: $ >>I agree with John, however the ideal towards which we are striving is multi- $ >>tasking operating systems and single-tasking processors. Admit it, don't $ >>you hate having your processor multi-task? $ > $ >Hello, no. Until you have something incredible like 64000 processors in your $ >box, you're going to find yourself running out of the suckers. If you have $ >a connection machine on your desk, great! If you've got a transputer, you $ >lose. What happens when you want to start up that 5th or 9th program and $ >you've only got 4 or 8 CPUs? $ $Then one of your processors starts to multi-task. Of course you never have $enough processors to handle everything, but it would be nice if you did. $It's an _ideal_. $ $The question was "Don't you hate having your processor multi-task" and the $answers have been "No, because it has to." If it didn't have to would you $want it to? Timesharing is a necessary evil, and we use it because we have $finite resources. We also use time sharing because even on existing time sharing systems, there is often a noticable percentage of *idle time*, when every single process on the system is waiting for i/o to complete. This is even true on *IX systems with disk cache hit rates of 80 and 90%. The truth is, on systems like sun workstations and the lot, if you take some process accounting statistics while you are running your c compile in background, and rogue in foreground, with emacs running the whole show, you still have easily 20% idle time on the cpu, even with little or no paging activity. Before you decide that your system isn't as fast as you'd like it to be because its multi-tasking, try looking at some system activity statistics for your system. -- Marc Mengel attmail!mmengel ...!{moss|lll-crg|mtune|ihnp4}!cuuxb!mmengel