Operating Systems · Processes and threads

The process abstraction

A running program's isolated illusion of its own CPU and memory, tracked by the OS as a process control block.

Also known as: process control block, PCB, process states.

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System calls and kernel mode: The controlled doorway, a trap into kernel mode, a program uses to ask the OS to do something on its behalf.

Process creation and control: The fork, exec, and wait calls that create, replace, and clean up processes.
Threads: Multiple independent execution paths sharing one process's address space.
CPU scheduling basics: The policy that decides which ready process runs next, and for how long.
Address spaces: Each process's private view of memory, starting at zero, that the OS maps onto real physical RAM.
Virtual machines and containers: Running an entire guest OS, or a lightweight container, on top of a host OS or hypervisor.