MAJOR ACHIEVEMENTS OF OS

HASTI SANGHANI

53003220022

 

ASSIGNMENT 2

MAJOR ACHIEVEMENTS

Operating systems are among the most complex pieces of software ever developed. This reflects the challenge of trying to meet the difficult and in some cases competing objectives of convenience, efficiency, and ability to evolve. [DENN80a] proposes that there have been four major theoretical advances in the development of operating systems:

• Processes
• Memory management
• Information protection and security
• Scheduling and resource management

Each advance is characterized by principles, or abstractions, developed to meet difficult practical problems. Taken together, these five areas span many of the key design and implementation issues of modern operating system

PROCESS:

A process is an entity that can be assigned to and executed on a processor. In the context of multiprogramming, timesharing and real-time transaction processing, process management is crucial. Coordinating multiple processes in a system requires handling the following situations:

• Improper synchronization - waiting for a signal that may never occur or that multiple signals could be received.
• Failed mutual exclusion - Mutex is used in controlling access to a shared variable
• Nondetermininant program operation - overwriting share memory may lead to this nondeterminism.
• Deadlocks - holding resources while waiting for others and two or more processes doing the same

A process has these components

• the executable code
• the data space
• execution context: registers, PC, stack, etc.

MEMORY MANAGEMENT:

Here memory means main memory (RAM), and the term memory management specifies how to utilize the memory efficiently. So, the main task of memory management is ‘efficient memory utilization and efficient processor utilization. The responsibility of memory management are given as follows:

(i) Process isolation: It simply means that controlling one process interacts with the data and memory of another process.
(ii) Automatic allocation and management: Memory should be allocated dynamically based on the priorities of the process. Otherwise, the process waiting time will increase, which decreases CPU utilization and memory utilization.
(iii) Protection and access control: Do not apply protection techniques and access control to all the processes, better to apply to the important application only. It will save execution time.
(iv) Long-term Storage: Long-term storage of process reduces memory utilization.

INFORMATION PROTECTION AND SECURITY:

Here the term protection means that secure the resources and information from unauthorized persons. The operating system follows a variety of methods for protection and security.
Generally, the protection mechanism is mainly of three types:

(i) Access control: The operating system provides access permissions to the users about important files and applications.
(ii) Information flow control: The operating system regulates the flow of data within the system.
(iii) Certification: The operating system provides the priorities and hierarchies to the resources using this then we can control unauthorized processes.

SCHEDULING AND RESOURCE MANAGEMENT:

A key responsibility of the OS is to manage the various resources available to it (main memory space, I/O devices, processors) and to schedule their use by the various active processes

Goals are:

• Fairness - all processes proceed with their work at a reasonable rate
• Differential responsiveness - some processes are more important, others may be holding scarce resources
• Efficiency - maximize throughput, minimize response time, service many users