isolcpu, taskset, pthread_setaffinity.

What this CPU affinity and isolation interview question tests

This is an easy operating-systems question that tests your practical understanding of Linux kernel mechanisms for controlling thread placement and CPU isolation. Quant trading firms ask it to verify that candidates can reason about low-latency system tuning—specifically, how to pin threads to isolated cores to minimize context-switching overhead and cache pollution.

To approach questions like this, you need to understand the purpose and scope of each tool: how isolcpu removes cores from the kernel scheduler, how taskset binds a process or thread to specific CPUs, and how pthread_setaffinity gives threads fine-grained control over their own placement. The question rewards clear thinking about the order of operations and the interaction between kernel-level isolation and user-space affinity calls.

• CPU isolation and the kernel scheduler
• Process vs. thread affinity
• Context switching and cache locality
• Linux cgroup and cpuset interfaces