polling vs interrupt

Understanding polling versus interrupt-driven packet processing in low-latency networks

This is an easy conceptual question that tests your grasp of the tradeoffs between two fundamental packet-handling strategies in high-performance networking. It appears frequently in systems and networking interviews, especially at firms building ultra-low-latency infrastructure.

The question asks you to reason about why one approach tends to outperform the other in latency-sensitive environments. To answer well, you need to consider the mechanics of each strategy—how control flow is triggered, what overhead each incurs, and how those costs scale with traffic patterns. The key is understanding not just what each mechanism does, but the hidden costs lurking in the gaps between packet arrivals, CPU state transitions, and context switches.

• CPU cache locality and warm state preservation
• Interrupt handling overhead (context switching, exception dispatch)
• Busy-waiting versus blocking trade-offs
• Throughput saturation and tail latency