Async. I/O via io_uring

xNVMe support io_uring it does so by mapping the NVMe commands read and write from the NVM command-set to io_uring opcodes:

• IORING_OP_READ / IORING_OP_WRITE

  • Mapped when using xnvme_cmd_pass(..) with payload as contigous / fixed buffers

• IORING_OP_READV / IORING_OP_WRITEV

  • Mapped when using xnvme_cmd_passv(...) with payload as iovec

Passthru

If you are looking to do command-passthru, that is, send arbitrary user-defined NVMe commands via the Linux operating system NVMe-driver, then io_uring is not the interface to use. Rather, you can do:

• opts = {.sync="nvme", .async="io_uring_cmd"}

• opts = {.sync="nvme", .async="emu"}

• opts = {.sync="nvme", .async="thrpool"}

Or use a user-space driver such as provided via SPDK/NVMe and libvfn.