(no subject)

Aaras P VASA (avasa@cs.ucsd.edu)
Thu, 20 Apr 2000 09:05:54 -0700 (PDT)

hello sir
these are the two evals for today
aaras
STAR OS

The problem addressed in this paper is to design an operating system
to achieve parallelism in a multiprocessor environment
It wants to decide whether the task force is conducive for this
purpose and the design issues related to the OS facilities supporting
task forces

Star OS is made for the Cm* system.
It is an object-oriented system
i.e information is encoded and stored in objects.It uses capability based
authorization
It is also message based . it has an event mechanism and a mailbox type
of object to implement the message communicaion
Scheduling , which is an important issue in multiprocessors is achieved
by schedulers and lowlevel multiplexors

their exists inherent parallelism in multiprocessors which can be exploited.
in a multiprocessor environment the processes (of the task force) become
considerably smaller and interprocess communication and synchronization
become of a much greater importance
this paper states that it is uncertain how Star OS facilities will support
application task forces, but task forces still seem a great idea to exploit
parallelism.

MEDUSA: An Experiment In Distributed Operating System Structure

The goal of this paper is to build a distributed operating system and
to expolit the hardware to produce this modular , robust system which is also
efficient

this is also developed for the Cm* . the operating system is divided into
disjoint utilities. all programs are organised as task forces and the utilities
themselves are task forces.Each task force is a set of cooperating activities
the activies themselves contains a private and shared descriptor list
the activities of the utilities task foeces are spread among the
available processors.
it also contains the Utility descriptor list fro communication between
user activities and utilities and a external descriptor list for sharing
of address space

this seems like a great idea to develop a distributed operating system
but it will work mainly for programs which are parallel and can make
use of this hardware strucure.
Star OS provided a flexible high level set of facilities while
Medusa is more concerned with producing a highly distributed OS
structure that closely matches the hardware.
task forces in Medusa are more defined then in Star OS while protection
is better in Star OS
the choice among these two operating systems will be more application
and goal specific.