Interrupts in operating system

 

Interrupts are a mechanism in an operating system that allows the CPU to temporarily stop executing the current process and switch to a different task. Interrupts are triggered by external events, such as the arrival of new data from an I/O device, or the expiration of a timer. They are used to allow the operating system to efficiently manage multiple processes, and to handle events that require immediate attention.

In a typical operating system, there are two types of interrupts: hardware interrupts and software interrupts. Hardware interrupts are triggered by external devices, such as a keyboard or a network adapter, while software interrupts are triggered by the operating system itself, for example, to handle system calls or to switch between processes.

When a hardware interrupt occurs, the CPU stops executing the current process and switches to the interrupt handler for the device that triggered the interrupt. The interrupt handler is responsible for processing the interrupt and returning control to the original process. For example, when a keyboard interrupt occurs, the interrupt handler reads the keyboard data, adds it to a buffer, and returns control to the process that was executing before the interrupt.

Here's an example of how a hardware interrupt works in an operating system:

1. The keyboard sends an interrupt signal to the CPU.
2. The CPU stops executing the current process and switches to the interrupt handler for the keyboard.
3. The interrupt handler reads the keyboard data and adds it to a buffer.
4. The interrupt handler returns control to the original process.

Software interrupts are triggered by the operating system itself, and are used to handle system calls or to switch between processes. System calls are requests made by a process to the operating system to perform a specific task, such as reading from a file or creating a new process. When a system call is made, the operating system triggers a software interrupt, which causes the CPU to switch to the system call handler. The system call handler is responsible for processing the request and returning control to the original process.

Here's an example of how a software interrupt works in an operating system:

1. A process makes a system call to read data from a file.
2. The operating system triggers a software interrupt.
3. The CPU stops executing the current process and switches to the system call handler.
4. The system call handler reads the data from the file and returns it to the process.
5. The system call handler returns control to the original process.

Interrupts are an important mechanism for managing multiple processes in an operating system. By allowing the CPU to switch between processes, interrupts allow the operating system to efficiently allocate resources and manage I/O operations. Interrupts also provide a way for the operating system to handle events that require immediate attention, such as the arrival of new data from a network adapter or the expiration of a timer.

In conclusion, interrupts are a powerful mechanism in an operating system that allows the CPU to temporarily stop executing the current process and switch to a different task. They are used to handle events that require immediate attention, to efficiently manage multiple processes, and to handle system calls and I/O operations. Understanding the role of interrupts in an operating system is essential for developing effective algorithms for managing processes and resources, and for ensuring that the operating system is able to respond to events in a timely and efficient manner.