CPUPinning

CPUpinning is the practice of binding one or more processes or threads to specific CPU cores. By restricting execution to a known subset of CPUs, the operating system scheduler can improve cache locality, reduce context switches, and increase predictability for CPU-bound workloads. Pinning does not increase overall CPU capacity, but it can make performance more consistent, particularly on systems with large caches or busy multi-core CPUs.

Implementation and tools vary by platform. On Linux, affinity is controlled via sched_setaffinity, the taskset command, or cpuset cgroups to assign CPUs to a process or a group of tasks. Typical examples include taskset -c 0-3 myapp to bind to cores 0 through 3, or configuring a cpuset for a multi-threaded service. Windows provides SetProcessAffinityMask for process-wide pinning and SetThreadAffinityMask for individual threads. Container environments such as Docker can restrict execution to specific CPUs with --cpuset-cpus. In virtualization and NUMA setups, pinning may interact with memory locality and virtual CPU scheduling.

Considerations and trade-offs: Pinning can improve performance for CPU-intensive tasks, but may reduce general throughput and lead to load imbalance if poorly configured. It can complicate scheduling for the OS and hinder responsive handling of interrupts or other tasks. Pinning decisions should consider the workload's parallelism, memory locality, NUMA topology, and whether cores or hyper-threaded logical processors are being used. Use cases include high-performance computing, databases, real-time systems, and benchmarking; avoid blanket pinning on general-purpose servers.