Poll position.

Understanding poll and epoll in Linux networking systems

This is an easy question on the networking APIs that power efficient I/O multiplexing in modern systems. It tests your grasp of how poll and epoll work at the UNIX/Linux level—a foundation for building low-latency trading infrastructure or any production system that handles many concurrent connections.

The question asks you to distinguish between the behaviour, design, and trade-offs of these two syscalls. To answer it, you should understand the fundamental differences in how each API scales with the number of file descriptors, how they report events, and when each is preferable. Quant trading firms care about this because they operate systems handling thousands of market connections simultaneously, where the choice between polling mechanisms directly affects latency and throughput.

• File descriptor monitoring and event-driven I/O
• Scalability and kernel implementation differences
• Edge-triggered vs. level-triggered notification modes
• Practical trade-offs in production systems