A process is an executing program, and this process goes via different states throughout the life cycle that is known the process states. Therefore, we will explore about what is process in OS with their terminology in detail; involving with different types of process in operating system with ease. This is unique article over the internet about Process in Operating System and its Types.
What is Process in Operating System?
In operating systems, a process refers to an executing program or a collection of related tasks that are treated as a unit of work. When a program is run, the operating system creates a process to manage it. The process contains all the necessary information and resources required to execute the program, such as the program code, memory space, data, open files, and other system resources.
Processes are managed by the operating system’s kernel, which is responsible for allocating resources, scheduling tasks, and managing inter-process communication. Each process has its own virtual memory space, which is isolated from other processes. This allows processes to operate independently and prevents them from interfering with each other. The operating system scheduler determines which process should be executed next, based on factors such as priority, CPU utilization, and resource availability.
Processes can communicate with each other using inter-process communication mechanisms provided by the operating system, such as pipes, shared memory, and message queues. This allows processes to exchange data and coordinate their actions.
Components of Process
A process has its own memory space, program counter, stack, and other resources that it needs to run. Here are the components of a process in operating system:
Stack: The stack is a region of memory used to store temporary data, such as function calls and local variables.
Heap: The heap is a region of memory used for dynamic memory allocation.
Data Section: The data section is a region of memory used to store global and static variables.
Text Section: This section contains the compiled program code, which read in from the non-volatile storage whenever the program is launched.
Process Life Cycle
The process life cycle in an operating system refers to the different states that a process goes through during its execution. The process life cycle can be divided into five main states:
Different Process States:
New: In this state, the process is being created, and its resources are being allocated by the operating system.
Ready: In this state, the process is waiting to be assigned to a processor. The process is ready to run, but it is waiting for the CPU to be available.
Running: In this state, the process is actively being executed by the processor. The process is using the CPU to perform its task.
Waiting: In this state, the process is unable to run, because it is waiting for some external event or resource, such as input/output or a lock to be released.
Terminated: In this state, the process has completed its execution or has been terminated by the operating system. The resources allocated to the process are freed by the operating system.
The process life cycle is managed by the operating system’s scheduler, which is responsible for deciding which processes should be assigned to the CPU and in what order. The scheduler uses various algorithms to determine the priority of each process and how long each process should be allowed to run before being pre-empted.
Process Control Block
A Process Control Block (PCB) is a data structure used by operating systems to manage information about a running process. It contains information about the process, including its process ID, priority, memory allocation, open files, CPU registers, scheduling information, and other essential data.
The operating system uses the PCB to keep track of each process’s state and to switch between processes quickly and efficiently. When a process is created, the operating system creates a new PCB and initializes it with the process’s information. As the process runs, the operating system updates the PCB to reflect the process’s current state, such as when it is waiting for input or executing a particular instruction.
The PCB is also essential for managing the process’s resources, such as CPU time, memory, and input/output devices. The operating system uses the information in the PCB to allocate and deallocate resources as needed and to ensure that processes do not interfere with each other.
Process control block consists the some essential information about the certain process. You can also say it the task control block. This information is about:
A process is an instance of a program in execution. The process state refers to the current condition or status of a process at a given moment in time.
There are several process states, which may vary depending on the specific operating system, but some of the most common ones include:
Running: The process is currently executing on one of the CPU cores.
Waiting: The process is waiting for an event, such as user input, completion of an I/O operation, or a signal from another process.
Ready: The process is ready to run but is waiting for a CPU to become available.
Sleeping: The process has been put to sleep by the operating system, either because it requested a delay or because it is waiting for a specific event to occur.
Zombie: The process has completed its execution, but its exit status has not yet been collected by its parent process.
Suspended: The process has been stopped temporarily, and its state has been saved to memory. It can be resumed later.
The process helps the kernel to manage system resources efficiently and to schedule processes in a fair and timely manner.
Process privileges refer to the level of access or permissions that a process (program or application) has within an operating system.
In an operating system, different processes may require different levels of access to perform their intended functions. For example, a system-level process may need high-level privileges to access critical system resources such as hardware, while a user-level process may only need limited access to specific user files.
Operating systems provide different levels of process privileges through the use of user accounts and groups. Each user account is associated with a set of privileges, which determine the actions that the user can perform on the system.
The operating system also defines a set of groups, each of which is associated with a set of privileges. A process can be assigned to a specific group, which determines the privileges that the process has.
Process ID (PID) is a unique identifier that is assigned to each running process. The PID is used to track the process in the operating system’s process table and is often used by system administrators and developers to monitor and control system processes.
In the Python os module, the getpid() function can be used to get the current process ID of the running Python process. Here’s an example:
pid = os.getpid()
print(“Current process ID:”, pid)
This will output something like:
Current process ID: 12345
Where 12345 is the current process ID
The pointer in the PCB typically points to the process’s Page Table, which is a data structure used by the operating system to keep track of which parts of the process’s memory are currently in physical memory and which parts are stored on disk.
When the operating system switches from one process to another, it updates the Page Table pointer in the PCB of the currently running process to reflect the current state of the process’s memory. This allows the operating system to keep track of the memory usage of each process and to efficiently manage the allocation of physical memory resources to different processes.
The program counter (PC) is a register that stores the address of the next instruction to be executed in a program. When a program is executed, the OS loads the program’s instructions into memory and sets the program counter to the address of the first instruction.
As the program executes, the program counter increments to point to the next instruction to be executed. The program counter is a crucial component of the CPU’s execution cycle, as it determines which instruction should be fetched from memory and executed next.
The OS also uses the program counter to keep track of the execution context of each process. When the CPU switches between processes, the OS saves the current value of the program counter and restores it when the process is resumed, allowing the process to continue executing from where it left off.
A CPU register is a small amount of memory within a CPU that is used to store data or instructions temporarily. Registers are essential components of a CPU because they allow the CPU to quickly access and manipulate data without having to read from or write to external memory.
Registers are typically very fast and can be accessed by the CPU much more quickly than main memory. In addition, because registers are located within the CPU itself, they are often referred to as being “on-chip” or “internal” memory.
There are different types of registers in a CPU, each with its own specific purpose. Some common types of CPU registers include:
Program Counter (PC) Register: It stores the memory address of the next instruction to be executed.
Instruction Register (IR) Register: Stores the current instruction being executed by the CPU.
Memory Address Register (MAR) Register: Stores the memory address of data to be read from or written to.
Memory Data Register (MDR) Register: Stores data being read from or written to memory.
Accumulator (ACC) Register: Stores intermediate results during arithmetic and logical operations.
Status Register (SR) Register: Stores status flags that indicate the outcome of previous operations, such as whether a previous operation resulted in a zero or overflow.
CPU Scheduling Information:
CPU scheduling is a process that manages the allocation of a computer’s central processing unit (CPU) among different tasks or processes. In a multitasking operating system, CPU scheduling plays a critical role in ensuring that all tasks receive fair access to the CPU and that the system remains responsive.
Some important concepts related to CPU scheduling are:
Process: A process is an instance of a program in execution. Each process has its own set of system resources such as memory, file handles, and CPU time.
CPU Burst: A CPU burst is the amount of time that a process requires to execute on the CPU.
CPU Scheduler: The CPU scheduler is responsible for selecting the next process to run on the CPU.
Context Switch: A context switch is the process of saving the current state of a process and restoring the state of another process.
Scheduling Algorithm: A scheduling algorithm is a policy that determines the order in which processes are scheduled on the CPU.
Memory management is a critical aspect of computer systems that involves managing the allocation and use of memory resources. Here are some key pieces of information about memory management:
Memory is Finite Resource: Memory is a finite resource, and computer systems must manage memory usage to prevent running out of memory.
Virtual Memory: Many modern operating systems use virtual memory to extend the available memory beyond the physical memory installed on a computer. Virtual memory uses a portion of the hard drive as additional memory when the physical memory is full.
Memory Allocation: When a program is executed, the operating system allocates a portion of memory to the program. This allocation is usually in the form of memory blocks or pages.
Memory Fragmentation: Over time, memory blocks can become fragmented, leading to inefficiencies in memory usage. Memory fragmentation can be reduced through memory defragmentation, which moves data around in memory to create larger contiguous blocks.
Memory Leaks: Memory leaks occur when a program does not release memory that it has allocated, leading to the program using up more and more memory over time.
Garbage Collection: Garbage collection is a technique used by some programming languages to automatically release memory that is no longer being used by a program.
Swapping: Swapping is a technique used by some operating systems to move pages of memory between physical memory and the hard drive. This allows the operating system to free up physical memory for other processes.
This information represents the total number of resources that are consumed by the system like as CPU time of a process, time limit and process numbers.
I/O Status information:
I/O (Input/Output) status information typically refers to the current status of data transfers between different components of computer system, such as between the CPU, memory, and peripheral devices like disks, network interfaces, and keyboards.
In most operating systems, I/O status information can be accessed through system utilities or APIs (Application Programming Interfaces) that provide visibility into the ongoing I/O operations. This information can include metrics such as the number of bytes read or written, the rate of data transfer, and the amount of data currently waiting to be processed.
Overall, the PCB is a critical data structure in operating systems, as it allows the operating system to manage multiple processes concurrently and to ensure that each process has the resources it needs to run correctly.
Process vs Program
In operating system, a process is a compiled computer program that is being executed by one or many threads. A program, on the other hand, is a set of instructions or code that is compiled and stored on disk, waiting to be executed.
The key difference between a process and a program is that a program is a static entity, while a process is a dynamic entity. A program is a group of the instructions that are installed into memory and executed by the computer. A process, on the other hand, is an instance of a program that is running in memory.
Whenever a program is installed into memory and to be executed, it will become a process. The operating system creates a process to run the program, and the process is managed by the operating system. The operating system provides the process with the necessary resources such as memory, CPU time, and other resources required for its execution.
In short, a program is a static set of instructions that is stored on disk, while a process is a dynamic entity that is created by the operating system when a program is loaded into memory and executed. The operating system manages the process and provides it with the necessary resources to execute the program’s instructions.
Process scheduling is a fundamental function of operating systems that manages the allocation of CPU time to multiple processes. The main goal of process scheduling is to maximize the utilization of the CPU and provide a fair and efficient allocation of resources to running processes.
There are different types of scheduling algorithms, including:
First-Come, First-Served (FCFS): This algorithm assigns CPU time to the process that arrives first and waits for it to finish before moving on to the next process.
Shortest Job First (SJF): This algorithm assigns CPU time to the process with the shortest estimated run time, aiming to minimize the average waiting time.
Priority Scheduling: This algorithm assigns CPU time to processes based on their priority, where the highest-priority process is given the CPU first.
Round Robin (RR): This algorithm assigns CPU time to processes in a fixed time quantum. Each process is allowed to run for a specified time, and the CPU is then allocated to the next process in the queue.
Multi-Level Feedback Queue (MLFQ): This algorithm uses multiple queues and scheduling policies to assign CPU time to processes. Each queue has a different priority level, and processes can move up or down the queues based on their behavior and resource needs.
The choice of scheduling algorithm depends on the requirements of the system and the workload of the processes. A good scheduling algorithm should ensure that all processes get a fair share of the CPU time and minimize the waiting time of processes.
Different Types of Process
Processes are classified into different categories depending about how much time they consume while performing their I/O operations like as:
I/O Bound Processes:
In operating systems, I/O-bound processes are those that spend most of their time waiting for input/output (I/O) operations to complete. When a process issues an I/O operation, it typically goes into a blocked or waiting state, during which time the CPU can switch to another process that is ready to execute. The blocked process remains in this state until the I/O operation completes, at which point it becomes ready to execute again.
I/O-bound processes are common in systems that handle large amounts of data or perform heavy I/O operations, such as file servers, database servers, and multimedia applications. These processes can benefit from using techniques such as asynchronous I/O, multi-threading, and caching to improve performance and reduce the amount of time spent waiting for I/O operations to complete.
Operating systems typically use a variety of scheduling algorithms to manage I/O-bound processes, such as the Completely Fair Scheduler (CFS) in Linux and the Windows I/O Manager in Windows. These algorithms aim to balance the needs of both CPU-bound and I/O-bound processes to ensure that all processes are executed efficiently and fairly.
CPU Bound Processes:
CPU-bound process is a type of process that requires a significant amount of CPU time to complete its execution. CPU-bound processes are generally characterized by long periods of computation without requiring much interaction with external I/O devices.
Examples of CPU-bound processes include scientific simulations, data processing, and mathematical computations. These processes typically perform a large number of calculations, iterations, or data manipulations, which consume most of the CPU’s time and resources.
CPU-bound processes can be challenging to manage in an operating system, especially in a multi-tasking environment where several processes compete for CPU time simultaneously. If the operating system does not manage the CPU resources efficiently, CPU-bound processes can hog the CPU, making the system unresponsive and causing other processes to starve for CPU time.
To handle CPU-bound processes, the operating system typically employs scheduling algorithms to prioritize CPU usage and allocate resources fairly among competing processes. In addition, some operating systems use techniques such as process preemption, time-sharing, and dynamic priority adjustment to ensure that CPU-bound processes do not monopolize the CPU and affect the system’s overall performance.
Other Types of Processes :
There are several types of processes in an operating system, including:
User Processes: These are processes that are initiated and controlled by users, such as applications or programs that are run by users.
System Processes: These are processes that are initiated and controlled by the operating system itself, such as device drivers, input/output (I/O) handlers, and system daemons.
Batch Processes: These are processes that are submitted in groups or batches, and executed without user interaction, such as background tasks or jobs that are scheduled to run at a specific time.
Real-Time Processes: These are processes that require immediate response from the operating system, such as control systems or multimedia applications that require high-speed processing.
Interacting Processes: These are processes that communicate and interact with each other through inter-process communication (IPC) mechanisms, such as shared memory, pipes, or sockets.
Threaded Processes: These are processes consist of multiple threads of execution that share the same memory space such as multithreaded applications; they can perform multiple tasks simultaneously.
In general, the process scheduling algorithm decides which process to run next based on a set of criteria. The scheduling algorithm takes into account the priority of the process, the amount of CPU time already used by the process, the arrival time of the process, and other factors.
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