What is the interrupt and how is it handled by an Operating System?
What is the interrupt and how is it handled by an OS?
Ask by Revati S Misra
Updated 27 Mar 2023
An interrupt is a signal generated by either hardware or software to the CPU, which temporarily halts the currently executing program and transfers control to a special program called an interrupt handler or interrupt service routine (ISR). Interrupts are used to handle events that require immediate attention, such as input/output (I/O) operations, hardware failures, and time-sharing interrupts.
When an interrupt occurs, the CPU saves the current state of the program being executed, including the values of the CPU registers and the program counter, onto the stack. The CPU then jumps to the interrupt vector table, which contains the memory address of the appropriate interrupt handler for the specific type of interrupt that occurred. The interrupt handler then executes, which may involve accessing or updating device or memory registers, performing I/O operations, or executing specific code to handle the interrupt.
The operating system (OS) manages the interrupt handling process by providing the interrupt handlers and setting up the interrupt vector table. The OS also prioritizes interrupts to ensure that more critical interrupts are handled before less critical ones.
The OS also has to deal with re-entrance, which is a situation where the interrupt handler itself generates an interrupt. To handle re-entrance, the OS may use a software interrupt queue, where each new interrupt is queued and handled after the previous interrupt is finished.
After the interrupt handler has completed its task, it restores the state of the interrupted program from the stack, and the CPU resumes execution from the point where it was interrupted.
Overall, interrupts play a critical role in computer systems by allowing the CPU to handle events in a timely and efficient manner, and the OS is responsible for managing this process.