Question

Discuss importance of interrupt of different types of efficient functioning of parallel and distributed operating system.

Answer 1

Hi,

Multitasking is parallel/concurrent execution of multiple tasks over a given period of time.

The interrupts are come as new tasks. Based on how the context switch via interrupts happens. it can happen at fixed intervals (preemptive multitasking) or program can say I can be interrupted (cooperative multitasking).

Interrupt based preemptive multitasking allows the system to more reliably guarantee each process a regular slice of cpu time. Such interrupts allow system to deal very fast to events for example: incoming data or immediate need to transfer resources to another program.

In preemptive systems, programs often poll or wait for input (like disk read) or CPU time. During this time, system is unable to do any useful work. Thus the inventions of interrupts and multitasking, such input waiting processes or cpu time waiting processes could be put on hold, pending the arrival of data. Thus system can be put to be used by other programs.

Then later on arrival of waiting data triggers a interrupt and processes on hold will be given a guaranteed time to process and move ahead.

Another area where interrupts were useful is real time programming systems where n number of unrelated activities must be controlled. In such systems, a interrupt system based on hierarchical system coupled with prioritization of process make sure all unrelated activities were given their share of cpu time.

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On a broader level, there are two types of interrupts: Hardware level and software level.

Digging deeper, there 4 types of interrupts (see the official one liner description below);

Level-triggered: an interrupt signaled by maintaining the interrupt line at a high or low logic level.

Edge-triggered: an interrupt signaled by a level transition on the interrupt line, either a falling edge (high to low) or a rising edge (low to high).

Message-signaled: A message-signaled interrupt does not use a physical interrupt line. Instead, a device signals its request for service by sending a short message over some communications medium, typically a computer bus.

Doorbell: In a push button analogy applied to computer systems, the term doorbell or doorbell interrupt is often used to describe a mechanism whereby a software system can signal or notify a computer hardware device that there is some work to be done.