Process Wrap Up

In this chapter, we looked at the famed operating system abstraction of the process. We discussed the generalities of the process, why it is important, and the relationship between processes and threads. We then discussed how Linux stores and represents processes (with task_struct and thread_info), how processes are created (via clone() and fork()), how new executable images are loaded into address spaces (via the exec() family of system calls), the hierarchy of processes, how parents glean information about their deceased children (via the wait() family of system calls), and how processes ultimately die (forcefully or intentionally via exit()).

The process is a fundamental and crucial abstraction, at the heart of every modern operating system, and ultimately the reason we have operating systems altogether (to run programs).

The next chapter discusses process scheduling, which is the delicate and interesting manner in which the kernel decides which processes to run, at what time, and in what order.