Polling is a technique used in computer systems to continuously check the status of a device or resource by the CPU.
Instead of relying on external events to trigger actions, the CPU actively queries the device to determine if it needs service.
Polling is a method where the periodically checks a device to see if it needs attention.
Use Cases for Polling
Polling is commonly used in situations where the latency of handling the device's requests is predictable and consistent.
It's often employed in simple systems where the overhead of interrupts is unnecessary, such as polling for keyboard input in simple embedded systems.
Advantages of Polling
Simplicity
Polling is relatively straightforward to implement and understand, making it suitable for simple systems.
Control
The CPU has direct control over when to check the status of the device, allowing for precise timing and coordination.
One advantage of Polling is that it is easier to implement for simple devices.
Disadvantages of Polling
Inefficiency
Polling can be inefficient as it ties up the CPU, especially if the device doesn't require immediate attention. This can lead to wasted CPU cycles.
High Overhead
Continuous polling can result in high overhead, consuming system resources unnecessarily.
Polling can result in higher CPU utilization compared to Interrupts, which can lead to issues.
Interrupts
Interrupts are a mechanism used in computer systems to handle asynchronous events.
When a device requires attention, it interrupts the CPU's normal execution flow, causing it to suspend its current operation and jump to an interrupt handler routine.
Interrupts
What is the main difference between polling and interrupts?
Use cases for Interrupts
Real-time Systems
Interrupts are essential in real-time systems where timely responses to external events are critical.
Device I/O
Interrupts are commonly used in handling input/output operations, such as data transfer between peripheral devices and memory.
Multitasking
Interrupts facilitate multitasking by allowing the CPU to switch between tasks efficiently.
Which method of communication is more suitable for handling sporadic events?
Advantages of Interrupts
Efficiency
Interrupts are generally more efficient than polling because they allow the CPU to perform other tasks until the interrupt occurs.
Low Latency
Interrupts typically have lower latency compared to polling since the CPU can respond immediately to an interrupt request.
Event-Driven
Interrupts are event-driven, meaning they only occur when necessary, reducing overall system overhead.
Interrupts provide a more efficient way for devices to gain the processor's attention compared to .
Which method of handling input/output is more suitable for real-time systems?
Disadvantages of Interrupts
Complexity
Implementing interrupts can be more complex than polling due to the need for interrupt handlers and managing interrupt priorities.
Overhead
While interrupts reduce overall system overhead, handling multiple interrupts and prioritizing them can introduce overhead and complexity.
Synchronization
Interrupt-driven systems may require synchronization mechanisms to ensure data consistency and prevent race conditions.
Interrupt Controller
An interrupt handler, also known as an interrupt service routine (ISR), is a special routine or function in a computer system that is responsible for handling interrupts generated by hardware devices or software signals.
When an interrupt occurs, the processor suspends its current execution and transfers control to the interrupt handler to service the interrupt
Handling interrupts requires the use of specialized hardware called an .
