Process concept and scheduling| Operating Systems| SNS Institutions скачать в хорошем качестве

Process concept and scheduling| Operating Systems| SNS Institutions

#designthinking #snsdesignthinkers #snsinstitutions Process Concept and Scheduling in Operating Systems A process is one of the core concepts in operating systems. It refers to a program in execution along with its current activity and allocated system resources. Unlike a program, which is a passive set of instructions stored on disk, a process is an active entity that resides in main memory and is executed by the CPU. The operating system manages processes to enable multitasking, improve system efficiency, and provide a responsive computing environment. When a program is executed, the operating system creates a process and assigns it a unique Process Identifier (PID). It also creates a Process Control Block (PCB), which stores important information such as the process state, program counter, CPU register values, scheduling information, and memory management details. The PCB acts as a record that allows the OS to manage and track every process effectively. During its lifetime, a process moves through several states. The new state represents a process being created. Once loaded into memory, it enters the ready state, waiting for CPU allocation. When the CPU starts executing it, the process moves to the running state. If the process needs to wait for I/O operations or an external event, it enters the waiting or blocked state. After completing execution, the process enters the terminated state, and the OS releases its resources. The movement of processes among these states is controlled by the process scheduler. Process scheduling is the mechanism by which the operating system decides which process should be executed by the CPU at any given time. Since multiple processes compete for CPU time, scheduling ensures fair and efficient allocation of this critical resource. Scheduling is broadly classified into three types: long-term, medium-term, and short-term scheduling. The long-term scheduler controls the admission of processes into the ready queue, the medium-term scheduler handles swapping processes in and out of memory, and the short-term scheduler selects the next process to execute on the CPU. Various CPU scheduling algorithms are used to optimize performance. First Come First Serve (FCFS) executes processes in the order of arrival. Shortest Job First (SJF) selects the process with the shortest execution time, minimizing average waiting time. Priority Scheduling assigns CPU based on priority levels, while Round Robin provides time-sharing by giving each process a fixed time slice. Each scheduling method has advantages and is chosen based on system requirements such as response time, throughput, and fairness. Effective scheduling also requires handling issues like starvation and context switching. Starvation occurs when a low-priority process never gets CPU time, which can be solved using aging techniques. Context switching is the process of saving the state of one process and loading another, allowing multitasking but introducing some overhead.