OpenBSD Disk I/O Performance: More Threads Aren't Always Better

This post benchmarks the random read/write and latency performance of a 1TB Crucial P3 Plus SSD on OpenBSD 7.7 using fio(1). Results show good I/O scalability in OpenBSD, but increasing job counts beyond an optimal point (6-8 concurrent jobs) degrades performance due to contention and CPU overhead. Compared to Linux, OpenBSD shows more sensitivity to concurrency in NVMe writes. The test also reveals that excessive threads significantly impact desktop responsiveness. Future tests will extend to USB storage.