fio vs stress-ng

fio is a free storage I/O workload simulator for performance testing and reproducing bugs. Its job files can define multiple threads, processes and files, with sequential, random or mixed reads and writes using buffered, direct or raw I/O. Tune block and I/O size, I/O engine, queue depth, target files or devices, and job count. Documented engines include Linux io_uring and libaio, POSIX asynchronous I/O, and synchronous read/write options. Separate engines support HTTP GET and PUT requests to WebDAV or S3 endpoints and access to Ceph RADOS and RBD. Verification options can check written data after a workload, including repeated burn-in tests. Results are available in normal text, terse, JSON and JSON+ formats, plus bandwidth and latency logs; terse output is intended for scripts, tables or graphs. fio supports Linux, Solaris, AIX, HP-UX, macOS, NetBSD, OpenBSD, Windows, FreeBSD and DragonFly. The HTTP engine supports direct I/O only at depth 1, with scaling through multiple jobs.

stress-ng has no write-up on Specifiction yet; its figures are above.