Interrupt handler in OS

Interrupt handlers play a crucial role in operating systems by managing time-sensitive events and facilitating efficient multitasking. Before discussing interrupt handlers, let's address the question, what is an interrupt?

In computing, interrupts are used to handle time-sensitive or urgent tasks, respond to external events, or communicate between different components of a computer system. When an interrupt occurs, such as an external event or hardware request, the normal execution of a program is temporarily suspended, and control is transferred to an interrupt handler.

This Answer explores the role, importance, and workings of interrupt handlers, along with different types of interrupt handlers and their specific functions.

Note: Interrupt service routine (ISR) is a specific code routine or function that is executed in response to an interrupt event. When an interrupt occurs, the processor transfers control to the ISR associated with that particular interrupt.

Interrupt handler

Interrupt handlers are responsible for handling interrupts promptly and effectively. Their primary role is to service interrupts and perform necessary actions associated with specific events. Interrupt handlers ensure that time-critical tasks, such as responding to user input or processing data from hardware devices, are addressed in a timely manner.

By suspending the execution of the current program, interrupt handlers help maintain system responsiveness and facilitate concurrent processing of multiple tasks.

Workflow of interrupt handlers

When an interrupt occurs, the processor first saves the current state of the interrupted program, including register values and the program counter. It then identifies the specific interrupt request (IRQ) associated with the event and acknowledges the interrupt. Next, the processor uses the interrupt number or IRQ line to locate the corresponding interrupt handler in the interrupt vector table (IVT). The control is transferred to the interrupt handler's memory address, where the necessary code is executed to handle the interrupt. The interrupt handler performs actions specific to the interrupt, such as interacting with hardware devices or processing data.

Once the interrupt is handled, the saved state is restored, and the interrupted program resumes execution from where it left off. This workflow ensures that interrupt events are promptly addressed while preserving the integrity of the interrupted program. By saving and restoring the program state, interrupt handling ensures that the interrupted program can seamlessly resume execution after the interrupt is serviced.

Types of interrupt handlers

As there are certain types of interrupts, similarly, there are some categories in interrupt handlers. The main types of interrupt handlers are:

1. Device-specific interrupt handlers.

2. Timer interrupt handlers.

3. Exception handlers.

4. Software interrupt handlers.

Now, let's discuss them in detail.

1. Device-specific interrupt handlers: They handle interrupts generated by devices like keyboards, mice, disk drives, and USB devices and interact with the corresponding hardware to perform actions such as reading or writing data.

2. Timer interrupt handlers: Timer interrupt handlers are responsible for handling interrupts triggered by hardware timers or system clocks. They manage time-related events and perform tasks such as task scheduling and preemptive multitasking.

3. Exception handlers: Exception handlers deal with exceptional conditions or events that occur during program execution, such as divide-by-zero errors, page faults, or invalid memory accesses.

4. Software interrupt handlers: Software interrupt handlers are triggered by software-generated interrupts, which are typically initiated through software instructions or system calls.

Applications of interrupt handlers

Interrupt handlers are widely used in modern operating systems as well as embedded systems due to their responsiveness and event-driven architecture that enables them to respond in real-time. Here are some fields where interrupt handlers are used:

• Networking and communication: Interrupt handlers are vital for networking and communication systems. They enable efficient data transfer, protocol handling, and network event management, contributing to reliable and responsive network communication.

• Multimedia and graphics processing: In systems that handle multimedia and graphics processing, interrupt handlers are used to handle interrupts related to audio, video, or graphical events. facilitating the smooth playback of audio and video streams.

• Power management: Interrupt handlers are involved in power management mechanisms, such as handling interrupts related to power state changes, sleep/wake events, or power-related events from hardware components. They assist in managing system power modes, transitions between power states, and power-related notifications, optimizing energy consumption and enhancing overall power efficiency.

Conclusion

In conclusion, interrupt handlers are essential components that contribute to the efficient operation, resource management, and performance of modern systems. They play a vital role in modern systems, providing efficient and timely handling of interrupts from various sources such as hardware devices, external events, or software requests. and are widely used in device drivers, real-time systems, networking, multimedia, power management, system monitoring, and I/O operations.