Interrupt vs. Polling

Attribute	Interrupt	Polling
Definition	Signals the processor to suspend its current execution and handle a specific event	Constantly checks the status of a device or process at regular intervals
Efficiency	More efficient as it allows the processor to focus on other tasks until an interrupt occurs	Less efficient as it requires constant checking of the device or process
Response time	Provides faster response time as it immediately handles the event	Slower response time as it depends on the polling interval
Resource usage	Uses fewer resources as it only activates when needed	Uses more resources due to constant checking

Introduction

Interrupts and polling are two common methods used in computer systems to handle external events. Both methods have their own advantages and disadvantages, and understanding the differences between them is crucial for designing efficient and responsive systems.

Interrupts

Interrupts are signals sent by external devices to the processor to request attention. When an interrupt occurs, the processor stops its current task and jumps to a specific interrupt handler to process the event. This allows the processor to respond quickly to external events without wasting time continuously checking for them.

One of the key advantages of interrupts is their ability to handle time-sensitive events in real-time. For example, in a system where data needs to be processed as soon as it arrives, interrupts can ensure that the processing is done promptly. This makes interrupts ideal for applications that require low latency and high responsiveness.

However, interrupts can also introduce complexity and overhead to the system. Managing multiple interrupts and prioritizing them can be challenging, especially in systems with a large number of devices. Additionally, interrupts can disrupt the normal flow of execution, leading to potential race conditions and synchronization issues.

Polling

Polling, on the other hand, is a method where the processor continuously checks the status of external devices to determine if they require attention. Unlike interrupts, polling does not rely on external signals to trigger a response from the processor. Instead, the processor actively polls the devices at regular intervals.

One of the main advantages of polling is its simplicity. Polling is easy to implement and does not require complex interrupt handling mechanisms. This makes polling a suitable choice for systems with a small number of devices or when the system requirements are not time-critical.

However, polling can be inefficient and wasteful in terms of system resources. Continuous polling can consume CPU cycles even when there are no events to handle, leading to increased power consumption and reduced overall system performance. Additionally, polling may introduce delays in responding to events, especially in systems with high device activity.

Comparison

When comparing interrupts and polling, it is important to consider the specific requirements of the system. Interrupts are well-suited for time-sensitive applications that require immediate response to external events. In contrast, polling may be more appropriate for systems where simplicity and resource efficiency are prioritized over real-time responsiveness.

• Interrupts are event-driven, while polling is time-driven.
• Interrupts are more responsive but can introduce complexity, while polling is simpler but less efficient.
• Interrupts are ideal for real-time applications, while polling may be sufficient for non-critical systems.

In conclusion, both interrupts and polling have their own strengths and weaknesses. The choice between the two methods ultimately depends on the specific requirements of the system and the trade-offs that need to be made in terms of responsiveness, complexity, and resource efficiency.