[rescue] The attention span of a mainframe...

[Ken Hansen]

Mainframe OSs (MVS et al) sieze control when you make an I/O request.

Your code never knows it gave up control, it just waits for the I/O
subsystem to return the requested information.

A tightly coded loop without any I/O or System calls would sieze control of
the system - for that reason, MVS and other environments have job time
components in their JCL (Job Contol Language). If your JCL "deck" doesn't
include a time, there is a system-wide default.

It is measured in seconds.

Just FYI,

Ken

----- Original Message -----
From: "Dave McGuire" <mcguire at neurotica.com>
To: <rescue at sunhelp.org>
Sent: Friday, August 03, 2001 10:03 PM
Subject: Re: [rescue] Mac Appliance


> On August 3, Brian Hechinger wrote:
> > >   Cooperative multitasking is multitasking in which each process must
> > > decide to give up control of the machine periodically...i.e.,
> > > user-process-controlled timeslicing.  In preemptive multitasking, the
> > > OS maintains control of the machine and "gives" each process
> > > timeslices.
> >
> > but doesn't that still "solve" the re-entrant issue?
>
>   Hmm...upon giving it some thought, I guess it does.  An application
> need only give up control when it's "ready", and won't be interrupted
> at just any random point.



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