NEW TRENDS IN OPERATING SYSTEM DESIGN

Welcome to all IGNOU MCA students. We will use this column regularly to discuss new developments, trends, new issues and challenges in computer fields which will be also supplemented with hypertext documents downloaded from different sites. The CD in this magazine contains tutorials on major operating systems: Unix, Linux, window 95, Mac and Solaris. From time to time, we will also inform you about activities going on in school which may be relevant to you.
Our inaugural column is "new trends in operating system design". We cover operating system in the first year as well the third year MCA syllabus.
There are 3 important factors which are driving new trends in operating System design.
1. New H/W
2. New Applications
3. New computing paradigm

New Hardware
There are generally 3 classifications of H/W architectures:

· Shared memory architecture (also called tightly coupled)
· Distributed Memory Architecture (loosely coupled)
· Hybrids

The most popular model of three is shared memory architecture because it is easy to program if number of nodes in the configuration is very less. But some of the fault tolerant research work has taken place around distributed memory configuration where it is easy to isolate faulty components.
A major H/W advancement that has affected O.S. is high-speed networks that can deliver data at gigabyte rates and beyond. One particular networking technology called ATM has been a major focus of the computer industry. High-speed network poses a problem to Operating System Network. Transfer of data is so fast that operating is not able to process it.

New Computing Paradigm
The traditional order of making with a computer is to buy programs to install them and run them locally. Today the network is the computer. With the emergence of the network, the traditional model will be replaced by the model in which users instead of buying and installing will log on to the Internet. Click on web pages, get applets (a small java program to do work for users possibly in conjunction with a remote server or database. Instead of filing the income tax form by hand or through a special program, users may be able to download income tax applets. The applet might ask some questions from the users, then connects their employers - Bank, LIC agents, Stock brokers to collect the required salary, interest and dividend information and display it for verification and submission. To support this trend, operating system has to support security technology, high bandwidth communication etc.
Nayeem Islam and other in communication of the ACM magazine, 1996, have identified 3 categories of research areas in O.S. design.
· Application specific O.S.
· Parallel and distributed O.S.
· O.S. support for high bandwidth communication including multimedia

Apart from these broad areas of research in O.S. design: two important trends which have been noticed in O.S. design are:
· Multithreading
· 64 bit operating system


We will discuss all these issues in the subsequent sections:
Application Specific Operating System
There have been 4 basic approaches to making operating system customizable and application/language specific.
1. Object technology approach
2. MicroKernel or NanoKernel approach
3. Web based approach
4. Language based application

Object Technology Approach
The important operating systems in this category are Choice O.S. and Spring operating system. The main advantage of these types of operating system is to optimize object-oriented application.
Microkernel or Nanokernel Approach
The concept of a kernel is known to Unix users. Most early Operating systems were designed by means of large monolithic kernel. A single kernel contained all the core functionalities of operating system-process scheduling file system management, device drivers and memory management, which made its design more, complicated. Today's trend is to make lightweight kernel, also called microkernel. This approach involves minimizing the kernel and implementing servers outside the kernel. The Microkernel implements only address space, interprocess communication and basic scheduling. All servers even device drivers run in user mode and are treated like any other application by the kernel. Since each server has its own address space, all these objects are protected from one another.
Web OS
The main driving force for web O.S. is the widespread use of Internet and its related applications. Since today's operating are quite heavy and slow, it can't be customized for web based application. In his article in IEEE computer, Franklin D. Reynolds has proposed an operating system for the web.
The main objective of web O.S. will be to simplify the development and deployment of new, innovative, distributed application. Mobile programming language such as Java and application resource and management will be an important component of web O.S. It will also support a broad range of security technology. Clicking on an icon will deploy new application and their associated resource management policies across the web.

Language based O.S.
There is also a trend to design an operating system for a specific language. Sun-Microsystems has developed an Operating system for optimizing java-based application.
Parallel and Distributed O.S.
There has been considerable recent interest in operating system for multiprocessor based system. The operating system for this type of architecture will support efficient sharing of all H/W resources - processors, memory and I/O devices for both parallel and multiprogrammed serial applications. Operating systems in this category are Hive, Sprite and Locus. Major H/W failure detection is an important component of design of these operating systems.

Operating System Support for High Speed Communication

The increase in high speed data transfer rate with emerging technologies such as ATM and fiber optics combined into the explosive growth in microprocessor performance have created a new type of application. Examples of such emerging applications are:
· Video Conferencing which includes audio and video transmission in real time.
· Supercomputing on cluster of workstations.

The success of these applications and technology is very mush dependent on how much operating system can make these network resources available to application programs. Unfortunately, the current O.Ses are threatening to become bottlenecks in delivering I/O data streams to application programs at high rates. The root cause of OS I/O bottleneck is limited memory bandwidth compared to CPU. Catch system can hide the slow speed of main memory only when the memory accesses generated by a program have good locality of references. Access to I/O data generated by O.S. and applications tend to have poor locality rendering the catch unable to avoid memory bottleneck in processing network I/O. Various techniques have been proposed to eliminate processing bottlenecks in high speed networking.

Operating system support for Multimedia

This trend started with window 95. Window 95 is a true multimedia O.S. In Window 95, you can create compound documents that include sound, video, graphics, charts, pictures and other elements from many different applications. Window 95 supports the Sony VISCA interface, which means that your application can control VCR & laser disc players. Window 95 supports a variety of industry standard sound and video compression codecs (coders/decoders). Codecs reduce the size of multimedia files and allow developers to distribute more contexts in a variety of formats.

Multithreading

This feature enables better CPU utilization time. A thread is just like a process having its own CPU cycle, stack, registers etc. but it is a lightweight process compared to a process which is called a heavyweight process. A process refers to a complete program whereas a thread could be a single statement of a program Switching over control from one thread to another thread (context switching) is faster than switching from one process (a program) to another. Interthreaded communication is faster than interprocess communication. Window 95, Windows NT all is examples of multithreaded O.S. One can do multiple tasks at once, while playing music in the background, one can surf Internet.

64 bit O.S.

Computer technology are becoming bigger and faster. Every 18 months processing power of microprocessor is getting doubled, pushing CPU clock speed for 33 MHz few years ago to 300 MHz now. Similarly O.S. architecture in moving from 32 bit to 64 bit to meet the demands of processor hungary application such as data warehousing, virtual reality and 3D graphics. Unix has already moved to 64-bit architecture.

A 64 bit address bus and OS can access upto 18 billion gigabytes.

Summary:
v In this article, we have identified major research areas and design trends in O.S. The materials provided with the CD will help you to know the design trends in major operating system. In the next articles, we will discuss how to learn operating system through Java applets.

References:

1. Evolving an operating system for the web, Franklin D. Reynolds, IEEE computer, September 1996.
2. Developments in O.S., Nayeem Islam & Prof. H.Campbell, Sept. 1996.
3. Your next O.S. - Dick Pountain, Byte Nov. 96.


SHASHI BHUSHAN

Back Reader, School of Computer Sc.

IGNOU