1 |
Mechanism |
Interrupt is considered a hardware mechanism. |
Pilling is a type of protocol. |
2 |
Procedure |
Device notifies CPU that it needs CPU attention. |
CPU constantly checks device status whether it needs CPU's attention. |
3 |
Service Provider |
Interrupt handler services the Device. |
CPU services the device. |
4 |
Definition |
An interrupt is an event that is triggered by external components other than the CPU that alerts the CPU to perform a certain action. |
Polling is an asynchronous activity that samples the status of an external device by a client program. |
5 |
Occurrences |
Interrupt can occur at any time. |
Polling occurs at regular intervals. |
6 |
Indication |
The interrupt-request line indicates that a device needs service. |
The command-ready bit indicates the device needs service. |
7 |
CPU Cycles |
CPU is disturbed only when a device needs servicing, which saves CPU cycles. |
CPU has to wait and check whether a device needs servicing which wastes lots of CPU cycles. |
8 |
Efficiency |
Interrupt becomes inefficient when devices keep on interrupting the CPU repeatedly. |
Polling becomes inefficient when the CPU rarely finds a device ready for service. |
9 |
Benefits |
Serves multiple devices, flexible, and efficient. |
Simple program, transmission reliability, and no need for additional chips. |
10 |
Drawbacks |
More complex and time-consuming. |
Standby time and CPU cycle waste. |
11 |
Example |
Let the bell ring then open the door to check who has come. |
Constantly keep on opening the door to check whether anybody has come. |