Resources | Subject Notes | Computer Science
The Operating System (OS) is a fundamental component of any computer system. It acts as an intermediary between the user and the hardware, managing system resources and providing a platform for applications to run. A core function of the OS is to perform various management tasks to ensure efficient and stable operation. This section details the key management tasks carried out by the OS.
Memory management is crucial for efficient utilization of the computer's main memory (RAM). The OS is responsible for allocating memory to processes, preventing conflicts between processes, and reclaiming memory when it's no longer needed.
The OS allocates memory blocks to processes when they request it and deallocates memory when a process terminates or no longer requires the allocated space.
Virtual memory is a technique that allows processes to use more memory than is physically available. The OS uses a combination of RAM and disk space (swap space) to create the illusion of a larger memory space. This involves techniques like paging and segmentation.
Paging divides both physical memory and virtual memory into fixed-size blocks called pages. The OS maps virtual pages to physical frames.
Segmentation divides memory into logical units called segments, which can vary in size. Each segment represents a logical part of a program (e.g., code, data, stack).
Process management deals with the creation, scheduling, and termination of processes. A process is a program in execution.
The OS creates new processes when programs are launched and terminates them when they finish or encounter errors.
Process scheduling determines the order in which processes are executed. The OS uses various scheduling algorithms (e.g., First-Come, First-Served, Shortest Job First, Priority Scheduling) to optimize CPU utilization and minimize waiting time.
Context switching is the process of saving the state of one process and restoring the state of another process. This allows the CPU to rapidly switch between different processes, creating the illusion of parallel execution.
The OS manages concurrent execution (multiple processes appearing to execute at the same time) and parallel execution (multiple processes executing simultaneously on multiple CPUs or cores).
I/O management involves controlling the flow of data between the computer and peripheral devices.
Device drivers are software components that allow the OS to communicate with specific hardware devices. They provide a standardized interface for accessing devices.
Interrupts are signals from hardware devices that require the OS's attention. The OS has interrupt handlers that respond to these signals and perform the necessary actions.
Buffering and caching are techniques used to improve I/O performance. Buffering involves temporarily storing data in memory to smooth out data transfer rates. Caching involves storing frequently accessed data in a faster memory location.
File management involves organizing and managing files on storage devices.
The OS organizes files into a hierarchical file system structure (e.g., directories, subdirectories).
The OS provides mechanisms to control access to files, ensuring that only authorized users can read, write, or execute them.
The OS manages the allocation of disk space to files.
System security is a critical aspect of OS management, protecting the system from unauthorized access and malicious software.
Authentication verifies the identity of users, while authorization determines what resources they are allowed to access.
Protection mechanisms prevent processes from accessing each other's memory or resources.
ACLs define the permissions for accessing files and other resources.
| Management Task | Description |
|---|---|
| Memory Management | Allocates and deallocates memory, manages virtual memory (paging, segmentation). |
| Process Management | Creates, schedules, and terminates processes; handles context switching. |
| I/O Management | Controls data flow to and from peripheral devices using device drivers, interrupts, buffering, and caching. |
| File Management | Organizes files in a file system, manages access control, and allocates storage space. |
| System Security | Ensures system integrity and confidentiality through authentication, authorization, and protection mechanisms. |