Xref: utzoo comp.sys.amiga.misc:49 comp.sys.amiga.advocacy:47 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!zaphod.mps.ohio-state.edu!lavaca.uh.edu!menudo.uh.edu!sugar!peter From: peter@sugar.hackercorp.com (Peter da Silva) Newsgroups: comp.sys.amiga.misc,comp.sys.amiga.advocacy Subject: Re: How do we change the scheduler? (Was Re: Multitasking at home...) Message-ID: <7504@sugar.hackercorp.com> Date: 13 Jan 91 00:34:10 GMT References: <17210@cbmvax.commodore. Organization: Sugar Land Unix - Houston Lines: 48 Followups-to: comp.sys.amiga.advocacy In article , mwm@raven.relay.pa.dec.com (Mike (My Watch Has Windows) Meyer) writes: > Actually, "true multitasking", as it is commonly _used_, means > preemptive multitasking. That's because all systems that were designed to multitask from day 1 use pre-emptive scheduling, *except for* a few Forth real-time systems with extremely tight memory budgets. Pre-emptive multitasking is what people for years meant by "multitasking". Polled multitasking was always considered a sort of poor cousin, and systems like Polyforth that depended on it were looked down upon. When people started referring to polled multitasking in terms that indicated they didn't know the difference between the two the terms "real" and "fake" multitasking showed up. > If you've got a reference to a textbook that > defines the term (in any way), I'd appreciate hearing about it. I've got 10 years of experience in the process control industry that defines the term that way. The usual reaction to hearing that Apple is claiming they've got a real O/S finally on the strength of their polled scheduler, among my co-workers, is "you've got to be kidding". > Bullshit. Explain to a user who doesn't have the foggiest idea what a > scheduler is why his machine - which, as far as he can tell, behaves > exactly like an Amiga under normal operation - has "fake" > multitasking. No problem. Just demonstrate that his machine doesn't behave exactly like an Amiga. Cut it down to 512K and watch it crash. Start up more thana couple of applications in a 2 Meg machine. Ask why the mouse is moving funny. Have him try to do anything useful while formatting a disk. Ask him why he can't run multifinder on a Mac Classic. > Actually, I think it's silly to define "true multitasking" at all. I agree. It's silly to even talk about a polled scheduler as "multitasking". > Either something is multitasking, or it isn't. I've already explained > how to tell which is which. If you insist on defining "true > multitasking", do it in non-technical terms. How about "no > non-privileged task can starve any other task"? Funny, people in the process control industry consider UNIX daft because a low priority task can still execute while there are higher priority tasks executing. How about defining "real multitasking" as "real-time multitasking"? At least that has a pretty good definition. -- Peter da Silva. `-_-' .