How does an operating system handle interrupt processing?

An operating system handles interrupt processing by temporarily halting the current process to address the interrupt request.

When an interrupt occurs, the operating system's role is to manage the interruption and ensure that the system's operations continue smoothly. The process begins with the CPU, which stops executing the current process and saves its state for later resumption. This is crucial as it allows the system to return to the exact point where it left off once the interrupt has been dealt with.

The operating system then identifies the type of interrupt and executes the corresponding interrupt service routine (ISR). The ISR is a specific piece of code designed to handle a particular type of interrupt. For instance, if the interrupt is a request from a peripheral device like a mouse or keyboard, the ISR will process the input and pass it to the appropriate software application. If the interrupt is a system error or exception, the ISR will attempt to resolve the issue or, if necessary, terminate the offending process.

Once the ISR has completed its task, the operating system will then restore the state of the CPU to resume the interrupted process. This involves reloading the process's saved state from memory, allowing it to continue from where it left off as if the interrupt had never occurred.

It's important to note that the operating system prioritises interrupts based on their urgency. Some interrupts, such as those indicating a system error, are given high priority and are processed immediately. Others, like peripheral device requests, are given lower priority and may be queued until the CPU is available.

In summary, the operating system plays a crucial role in interrupt processing. It ensures that interrupts are handled efficiently and effectively, allowing the system to continue operating smoothly despite the interruption. This involves saving and restoring the state of the CPU, executing the appropriate ISR, and prioritising interrupts based on their urgency.