From: Sellakumaran Kanagarathnam (sellak_at_windows.microsoft.com)
Date: Mon Jan 12 2004 - 12:47:07 PST
The authors begin with citing three then current different examples of
multiprogrammed systems and it was very interesting to note that an
airlines reservation system was an example.
The authors start with five properties of multiprogrammed computer
systems, explain the concepts and terminology that they are using,
supervisor (core of basic computer system functions), primitive
operations used for parallel processing. They then go on to explain what
they call as inferior spheres of protection, protected entry points and
end with a detailed explanation of the directories and naming system.
The five properties of MCS are: 1) concurrent operations for multiple
users 2) sharing pools of resources with problem of efficiently using
resources taken out from the users 3) demand for computing resources
vary and hence the amount of physical resources required is governed by
average demand rather than peak demand 4) common information shared by
multiple computations 5) MCS should be a modular multiprocessor system
so that modules can be added later on.
The authors go on to define the concepts and terminology. It is nice to
see security has been given due consideration at various levels
(different spheres of protection - c-list and so on). In this paper
also, a segment refers to both memory as well as retained objects
(files). A computation seems to correspond to a process in modern world
and a process seems to correspond to a thread.
A principal seems to represent individual users, a group and/or a
specific function.
The supervisor forms the core basic block of the MCS. Some of the Meta
instructions like fork and quit sound familiar but instructions like
join do not.
In discussing the inferior spheres of protection, it is very interesting
to note the exception handling facilities provided.
Directory naming: retained objects. The constraint that retained
objects' name cannot be changed reflects poor design and the second
reason given is a no reason.
The initial solution suggested for dealing with ambiguous names (an
awkward restriction being imposed), all these tend to imply that this
paper is one of the initial attempts to define characteristics and Meta
language for MCS.
Even though the paper refers to three practical systems and often refers
to MAC system, the ideas represented seem to be more of conceptual
nature and no referent to an actual system based on the concepts is
made.
The paper attempts to define a list of Meta instructions that can be
used in an MCS and while doing so it explains some of the concepts and
terminology used.
This archive was generated by hypermail 2.1.6 : Mon Jan 12 2004 - 12:46:59 PST