Module 2 Video 1 Processes and programs-Processes are active. (Dynamic) Act of executing a program.-Programs are passive. (Static) Stored in file.-A program can be run by many processes (separate or concurrent)-A process can run many programs -Example: Start process Identity – user id.
During its lifetime it can run multiple programs.-Linker: Uses relocation table to find lines of code to be replaced and then uses the symbol tables to find which functions have to be used.-Loader: takes the output of linker and copies them to memory.Video 24 things need memory: 1) global data2) code3) Stack4) Heap-In order to switch between process A and B, both processors have to be in ready state.Video 3Scheduling Metrics-CPU Utilization: Total CPU busy time/total time = (total time – idle time)/total time-Increase as much as possible-Turnaround time: P1 = 18s, P2 = 16sAverage turnaround time = 18+16/2 = 17s-Lowest turnaround time-Waiting time: don’t count initial waitIt’s The time a process waits in the ready queueP1: w1 = 3s P2: w2 = 0s-Reduce the wait time-Response time: how quickly a process responseP1: r1 = 0s , P2: r2 = 2s Avg = 0+2/2 = 1sVideo 4Pre-emptive schedulingTime quantaVideo 5
