A Program will not do anything unless a CPU executes its instructions. An executing program is called a process. The Process requires computer resources to complete its task. More than one process can exist in the system, which needs the same resources at the same time. So, the operating system handles all the resources and processes effectively.
There may be situations where many resources may need to be executed at the same time by one process so that consistency is maintained; otherwise, the system may become inconsistent, and there may be chances of deadlock.
The operating system performs the following tasks for process management:
- Suspending and restarting the process.
- Offering mechanisms for process communication.
- Offering mechanisms for process synchronization.
- Process scheduling and threads on the CPU.
- Create and delete system and user processes.
Process: - A process is defined as a program in execution.
Types of Processes
There are two types of Processes:
- I/O-Bound Process
- CPU-Bound Process
- I/O-Bound Process: - It is a type of process in which the process execution time is calculated with the help of the amount of time a process spends to complete the input/output operations.
- CPU-Bound Process: - CPU-Bound Process is another type of process in which the process execution time is calculated with the help of the CPU speed. If we use a faster processor, then the CPU-Bound Process may execute faster.
Components of Process
There are four components of the process:
- Text: - Text consists of the value of the program counter and the processor’s registers content that is represented by the current activity.
- Data: - Data contains both static as well as global variables.
- Stack: - Stack contains temporary data like local variables, return addresses, and method/function.
- Heap: - Heap is a dynamic memory which is allocated during the run time of a process.
Attributes of Process
The attributes of a process are also called the context of the process. These attributes design the Process Control Block (PCB).
The attributes used to store Process Control Block (PCB) are:
- Process ID
- Program Counter
- Process State
- General Purpose Registers
- List of open Files
- List of open Devices
Process ID: - Process ID is a unique ID that is assigned to the process at that time when the process was created.
Program counter: - The Program counter holds the address of the last instruction of the process.
Process State: - The process state may be one of the following states, i.e., running, ready, waiting, terminate, etc.
Priority: - Some priority is assigned to every process in the memory. The process that has the highest priority between the processes gets the CPU first.
General Purpose Registers: - These registers are used to store the data which is generated at the time of process execution.
List of Open Files: - A list of open files contains some files that require to be present in the main memory when the process is executing
List of Open Devices: - List of open devices contains the list of devices that are used when the process is executing.