ckp@grebyn.com (Checkpoint Technologies) (12/29/90)
In article <1990Dec28.000727.24394@zorch.SF-Bay.ORG> xanthian@zorch.SF-Bay.ORG (Kent Paul Dolan) writes: >Probably so; aging cpu bound processes to get lower priorities and i/o >bound ones to get higher priorities, and old processes to get higher >priorities is a fairly common refinement for multiple user multi-tasking >OSs. > >However, I would absolutely _hate_ priority aging on the Amiga, or any >single user machine, except perhaps as an option I have to specifically >_en_able. When I up the priority of my terminal session, since it is >almost 80% of the big chunks of time either waiting for keystrokes, or >waiting for new text from the host site to show up for the screen, my >extra three priority "points" have little effect; other processes get >almost all the cpu cycles. There is a way to satisfy everyone, and I've seen it implemented in several places. I've used a system called TSX Plus from S&H. It has a priority range from 1 to 99, where 99 is highest. However, these priorities are separated into three classes: 1-19 is the "background" class, where any runnable task higher than 20 superceeds one, and they are aged so all of them get some background cycles; 20-49 is "normal" class, where again aging takes place to give all tasks some cycles; 50-99 is "real time", where no aging takes place, and the highest priority runnable task superceeds all lower priority tasks. VMS implements the "real time" priority class as well, and I believe OS/2 has all three classes though the background class may behave differently. I also believe that OS9-68K implements a real time class, but I don't have a reference to back that up, and I recall OS9-6809 didn't. In any case, this gives you what you want when you want it. I would like to see some priority balancing within the Exec, not at the expense of strict priorities but as a supplement. -- First comes the logo: C H E C K P O I N T T E C H N O L O G I E S / / \\ / / Then, the disclaimer: All expressed opinions are, indeed, opinions. \ / o Now for the witty part: I'm pink, therefore, I'm spam! \/