CST334 - Week 25

I learned so much this week; I don't know if I can fit it into one post! Firstly, we learned all about the process. The reading and lectures covered process abstractions, how processes are created, the different process states, and introduced the idea of context switches. A process is the current running program and by virtualizing the CPU, we can create the illusion of many processes running at the same time. Context switches are when the current process stops running and OS chooses and starts the next process. Each time a process stops, the state of the process must be preserved and saved, including the contents of the registers, so that it can resume in the future. This leads to the question of how a CPU switches between processes, either voluntarily, such as when the program completes and terminates, or involuntarily, with timer interrupts. Next, I learned about different scheduling policies that determine which process to run next in a context switch. The scheduler must keep in mind response time, turnaround time, fairness, efficiency, and ensure that the scheduling policy is upheld at all times. One example is the Multi-Level Feedback Queue scheduler, which gives jobs different priorities to determine which ones to run first, while also allowing jobs to switch between levels so that all of the jobs get fair chances to run. Lastly, I worked on Lab 2 in which I practiced C programming and demonstrated a program with multiple processes using the fork(), exit(), wait(), and exec() system calls.