NVMe passthrough skips abstractions. To access NVMe de-
vices directly, io_uring provides the OP_URING_CMD opcode, which
issues native NVMe commands via the kernel to device queues. By
bypassing the generic storage stack, passthrough reduces software-
layer overhead and per-I/O CPU cost. This yields an additional 20%
gain, increasing throughput to 300 k tx/s (Figure 5, +Passthru).
Which userspace libraries support this?. Liburing does, but Zig's Standard Library (relevant because a tigerbeetler wrote the article) does not, just silently gives out corrupt values from the completion queue.
On the rust side, rustix_uring does not support this, but widely doesn't let you set kernel flags for something it doesn't support. tokio-rs/io-uring looks like it might from the docs, but I can't figure out how (if anyone uses it there, let me know).