CMSC 421 Exam 2 (100% Correct)

First-Come, First-Served Scheduling correct answers Processes are executed in order received. Convoy Effect - problem where long processes make shorter, potentially more important processes, wait. Shortest Job First Scheduling correct answers Schedule processes/jobs with shortest burst time first. Priority Scheduling correct answers Assign every process a priority Starvation is a risk - low priority processes may never execute. Use aging - increase priority of a process over time as a solution to starvation Round Robin Scheduling correct answers Each process gets an allotted amount of CPU time. After the time has elapsed, the process is added to the end of the ready queue. If process completes before time quantum expires, process will voluntarily give up CPU. Multilevel Queue Scheduling correct answers Hybrid of other scheduling types using queues. Processes are permanently assigned to their queues. A multilevel feedback queue however allows processes to move between queues. Algorithm Evaluation correct answers 1. How to select CPU-scheduling algorithm? i. Determine criteria, then evaluate algorithms. ii. Deterministic modeling: a. Type of analytic evaluation b. Takes a particular predetermined workload and defines the performance of each algorithm for that workload. 2. Little's Formula: n = λxW i. n = average queue length ii. λ = average arrival rate iii. W = average wait time Deadlocks occur if four conditions hold simultaneously correct answers Mutual Exclusion - Only one process at a time can use a resource.