To represent a process at high level the operating system uses the Process Control Block (PCB), which basically serves as the storage for all the data that is needed for a process to start, stop and restart.
Contains (among other things):
- process state
- Program counter, indicates the address of the next instruction to execute
- CPU registers
- CPU-scheduling information todo
- memory-management information
- I/O status information
In Linux the PCB is stored in kernel’s memory space, which is an area of memory not accessible by the user space. The place of the pointer for the task_struct is architecture dependant: on x86 at the end of task kernel stack, there is thread_info struct.
References
- A. Silberschatz, P. B. Galvin, e G. Gagne, «Operating System Concepts».
- https://stackoverflow.com/a/10605654
- https://linuxgazette.net/133/saha.html
See also
- In a process execution, it goes through many stages — the process state field in the PCB is exactly the state machine described there: new, ready, running, waiting, terminated
- A process in operating systems is a program in execution — the memory layout (stack, heap, text, data) is what the PCB’s memory-management information tracks and protects
- Tail Call optimization replaces call with jmp — the program counter field in the PCB is what gets saved and restored on context switches; TCO avoids pushing new return addresses precisely to reduce this overhead
- System Programming - Compile utilities — ThreadSanitizer detects race conditions that arise when the OS switches between processes, saving and restoring CPU registers and program counter via the PCB