CPU Scheduling Concepts

The maximum utilization of the CPU is achieved by keeping multiple processes active simultaneously, switching between them as needed.

The execution of a process involves a pattern of alternating CPU bursts (computation) and I/O bursts (waiting for input/output operations).

The distribution of CPU bursts for each process can vary in length. Some processes may have long bursts, while others may have short bursts. The scheduler needs to consider this when choosing which process to run next.

The CPU scheduler is a key component in the operating system that makes decisions about which process to run on the CPU at any given time.

The CPU scheduler selects a process from the 'ready' state and assigns the CPU to it. It makes these decisions based on various factors like the process's priority and its expected burst duration.

The dispatcher is responsible for giving control of the CPU to the process selected by the scheduler. It involves switching the context, mode, and jumping to the correct location in the program for execution.

Dispatch latency refers to the time it takes the dispatcher to switch from one process to another, including switching the context and preparing the next process for execution.

Preemptive scheduling allows the scheduler to interrupt a running process and switch to another process, often based on priority or time limits. Non-preemptive scheduling requires the currently running process to relinquish the CPU willingly.

The amount of time a process spends waiting in the ready queue before being selected for execution.

The total number of processes completed per unit of time. It measures how efficiently the system completes tasks.

The time it takes for a process to complete its execution, from arrival to completion.

The amount of time from when a request is submitted until the system produces the first response, not the final output.

A scheduling algorithm where the process that arrives first is the first to be executed. Processes are served in the order they enter the queue.

A scheduling algorithm that prioritizes processes with the shortest predicted CPU burst time. This can improve overall performance by reducing average waiting time.

A variant of SJF where once a process is assigned the CPU, it cannot be preempted until its CPU burst completes.

A metric that assesses the efficiency of the CPU, aiming to keep it busy as much as possible.

A scheduling algorithm that aims to minimize the total time a process spends waiting in the ready queue.

A scheduling objective prioritizing the shortest turnaround time, which means the fastest possible completion of tasks from start to finish.

A scheduling algorithm where the CPU is allocated to the process with the shortest remaining time (burst) until completion, considering both currently running and newly arrived processes. This approach ensures minimal average waiting time.

A non-preemptive scheduling algorithm where the CPU is allocated to the process with the shortest estimated burst time. It doesn't interrupt the currently running process, even if a new process arrives with a shorter burst time.

A scheduling algorithm where the CPU is allocated to the process with the shortest remaining time (burst) until completion, even if a new process arrives with a shorter burst time. This version allows interrupting the current process if a shorter task arrives.

A scheduling algorithm where each process is assigned a priority number. The CPU is allocated to the process with the highest priority (usually lower numerical value means higher priority). It can be preemptive or non-preemptive.

A problem in priority scheduling where low priority processes may never get to execute because higher priority processes keep arriving or have long bursts.

A solution to the starvation problem in Priority Scheduling where low priority processes gradually increase their priority over time, allowing them to eventually execute.

A scheduling policy where the CPU is assigned based on the estimated burst time of the processes, making it a variant of priority scheduling.

The average time processes wait for their turn to execute on the CPU is minimized in a system using the Shortest Job First (SJF) algorithm when compared to other scheduling algorithms.

The process that is currently running is interrupted by the scheduler and a different process takes over the CPU.

The running process relinquishes control of the CPU when it voluntarily completes its task. The scheduler then selects the next process to run.

A preemptive scheduling algorithm where the process with the highest priority gets the CPU. If a higher priority process arrives, it preempts the current one.

A scheduling algorithm where each process gets a fixed amount of CPU time called a "time quantum". After the time quantum, the process is put back in the ready queue. This ensures fair CPU distribution.

The average time a process spends waiting in the ready queue before it's executed. It's an important metric for evaluating scheduling algorithms.

A non-preemptive algorithm where processes are executed in the order they arrive in the ready queue. The currently running process keeps the CPU until it completes.