In-depth understanding of the computer operating system--8th chapter: Process

Process:

(1) The classic concept of a process is an instance of a program in execution.

(2) Each program in the system is running in the context of the process.

(3) Context: consists of the state required for the proper operation of the program, which includes: the code and data stored in the memory, its stack, the general purpose Register,

program counters, environment variables, and open file descriptors, and so on.

The key abstraction that the process provides to the program:

(1) Independent logic control flow: As if the program exclusive CPU processor at runtime

(2) Private address space: As if the program exclusive memory.

Logical control Flow:

The program runs with a series of values for the program counter (PC) that uniquely correspond to the instructions of the executable program. The sequence of these values is the logical control flow.

Concurrent streams:

The execution time of a logical stream overlaps with the collar of a stream called a concurrent stream.

For example, A and B overlap in time, a and C time overlap

and B and C, because the last instruction of B was executed when the first instruction of C was executed.

Multi-tasking:

The execution of a process in turn with other processes is called multi-tasking.

Time slices:

A process that executes a fragment on its control flow is called a time slice.

8.2.3 Private address space

In-depth understanding of the computer operating system--8th chapter: Process