introduction to advanced operating systems
- 2. What is an Operating System • An Operating System (OS) is a type of software that acts as an interface between a computer's hardware and its users (or application software). • It manages hardware resources, provides essential services for software applications, and ensures the smooth functioning of the system.
- 3. Key Functions of an Operating System Resource Management: •Manages hardware resources like CPU, memory, storage, and I/O devices. •Allocates resources efficiently to ensure optimal performance. Process Management: •Handles the execution of processes, including multitasking and process synchronization. •Manages process creation, termination, and scheduling. Memory Management: •Controls the allocation and deallocation of memory to processes. •Tracks free and used memory, and ensures no overlap or corruption.
- 4. File System Management: • Provides a structure for storing and organizing files on storage devices. • Manages file access, permissions, and directories. Device Management: • Acts as an intermediary between hardware devices and software applications. • Includes device drivers to control hardware components. Security and Access Control: • Protects the system from unauthorized access and threats. • Implements authentication, encryption, and access permissions. User Interface: • Provides interfaces for user interaction, such as Command-Line • Interface (CLI) or Graphical User Interface (GUI).
- 5. Mainframe Operating System A mainframe operating system is software that manages the resources and activities of large, and powerful mainframe computers. The mainframe operating system is designed so that it can handle multiple jobs simultaneously. To deal with large amounts of transactions is one of their features which is why they are used by large organizations such as banks, and governments. For example, IBM z/OS, and IBM z/VSE. The services provided by the mainframe operating system are:
- 6. Mainframe Operating System They perform operations like clustering and partitioning. They act as the base for extensive applications. It divides the jobs into different batches. It provides data security and efficient task management. It performs a large amount of transactions.
- 7. Applications of Mainframe Operating System Mainframe operating systems are used by governments in domains like education, health, defense, and infrastructure development because of their scalability and availability. It is used by transportation systems like railways, and airlines to manage their operations. It is used by enterprises that have to handle large databases every minute because of its high processing power and flexibility. Used by banks and financial institutions to handle large amounts of transactions made by credit cards and other mediums because they provide reliability, compatibility, and high security.
- 8. Advantages of Mainframe Operating System Mainframe operating system have very high and massive processing power. They are scalable and can handle large scale of users and applications. They are fault tolerant and reliable. They provide great security measures to protect the system from hacking and other cyber security threats. Disadvantages of Mainframe Operating System Mainframe operating system are very costly so only large institutions can afford them. They are very complex to operate. Specialized knowledge is required to use it. Mainframe Operating System aren't flexible. They aren't available so easily.
- 9. Advantages of Mainframe Operating System Mainframe operating system have very high and massive processing power. They are scalable and can handle large scale of users and applications. They are fault tolerant and reliable. They provide great security measures to protect the system from hacking and other cyber security threats. Disadvantages of Mainframe Operating System Mainframe operating system are very costly so only large institutions can afford them. They are very complex to operate. Specialized knowledge is required to use it. Mainframe Operating System aren't flexible. They aren't available so easily.
- 10. Process Scheduling Process scheduling is the activity of the process manager that handles the removal of the running process from the CPU and the selection of another process based on a particular strategy. Process scheduling is an essential part of a Multiprogramming operating system. Such operating systems allow more than one process to be loaded into the executable memory at a time and the loaded process shares the CPU using time multiplexing.
- 11. Categories of Scheduling Non-Preemptive: In this case, a process’s resource cannot be taken before the process has finished running. When a running process finishes and transitions to a waiting state, resources are switched. Preemptive: In this case, the OS assigns resources to a process for a predetermined period. The process switches from running state to ready state or from waiting state to ready state during resource allocation. This switching happens because the CPU may give other processes priority and substitute the currently active process for the higher priority process.
- 12. Types of Process Schedulers Long Term or Job Scheduler Short-Term or CPU Scheduler Medium-Term Scheduler
- 13. Long Term or Job Scheduler It brings the new process to the ‘Ready State’. It controls the Degree of Multi- programming, i.e., the number of processes present in a ready state at any point in time. It is important that the long-term scheduler make a careful selection of both I/O and CPU-bound processes. I/O-bound tasks are which use much of their time in input and output operations while CPU-bound processes are which spend their time on the CPU. The job scheduler increases efficiency by maintaining a balance between the two. They operate at a high level and are typically used in batch-processing systems.
- 14. It is responsible for selecting one process from the ready state for scheduling it on the running state. Note: Short-term scheduler only selects the process to schedule it doesn’t load the process on running. Here is when all the scheduling algorithms are used. The CPU scheduler is responsible for ensuring no starvation due to high burst time processes. Short-Term or CPU Scheduler
- 16. Medium-Term Scheduler It is responsible for suspending and resuming the process. It mainly does swapping (moving processes from main memory to disk and vice versa). Swapping may be necessary to improve the process mix or because a change in memory requirements has overcommitted available memory, requiring memory to be freed up. It is helpful in maintaining a perfect balance between the I/O bound and the CPU bound. It reduces the degree of multiprogramming.
- 18. Comparison Among Scheduler Long Term Scheduler Short Term Schedular Medium Term Scheduler It is a job scheduler It is a CPU scheduler It is a process-swapping scheduler. Generally, Speed is lesser than short term scheduler Speed is the fastest among all of them. Speed lies in between both short and long-term schedulers. It controls the degree of multiprogramming It gives less control over how much multiprogramming is done. It reduces the degree of multiprogramming. It is barely present or nonexistent in the time-sharing system. It is a minimal time-sharing system. It is a component of systems for time sharing. It can re-enter the process into memory, allowing for the continuation of execution. It selects those processes which are ready to execute It can re-introduce the process into memory and execution can be continued.
- 19. Context Switching In order for a process execution to be continued from the same point at a later time, context switching is a mechanism to store and restore the state or context of a CPU in the Process Control block. A context switcher makes it possible for multiple processes to share a single CPU using this method. A multitasking operating system must include context switching among its features. The state of the currently running process is saved into the process control block when the scheduler switches the CPU from executing one process to another. The state used to set the computer, registers, etc. for the process that will run next is then loaded from its own PCB. After that, the second can start processing.