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A process is an instance of a running program

We can add more to a process!

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Summary

The OS has to:

• Maintain process control blocks, including state
• Create new processes
• Load a program, and re-initialize a process with context

Process Control Block

PCBs contain all information, this is the task_struct in Linux and contains the following:

• Process state
• CPU registers
• Scheduling information
• Memory management information
• I/O status information
• Any other type of accounting information
• Each process gets a unique process ID (PID) to keep track of it!

Process State Diagram

How a kernel loads a program into memory

1. Created: kernel initializes the PCB and loads the program’s code, data, stack, and heap into memory
2. Waiting: process is ready to run but waiting for the CPU to be available