Changelog
=========

Upcoming release
----------------

- NVMe
  - The Weighted Round Robin arbitration method is now supported. This allows
    the user to specify different priorities on a per-I/O-queue basis.  To
    enable WRR, set the `arb_mechanism` field during `spdk_nvme_probe()`.
  - A simplified "Hello World" example was added to show the proper way to use
    the NVMe library API; see `examples/nvme/hello_world/hello_world.c`.
- NVMe over Fabrics
  - The configuration file format was changed, which will require updates to
    any existing nvmf.conf files (see `etc/spdk/nvmf.conf.in`):
    - `SubsystemGroup` was renamed to `Subsystem`.
    - `AuthFile` was removed (it was unimplemented).
    - `nvmf_tgt` was updated to correctly recognize NQN (NVMe Qualified Names)
      when naming subsystems.  The default node name was changed to reflect this;
      it is now "nqn.2016-06.io.spdk".
  - Many bug fixes and cleanups were applied to the `nvmf_tgt` app and library.

v16.06: NVMf userspace target
-----------------------------

This release adds a userspace NVMf (NVMe over Fabrics) target, conforming to the
newly-released NVMf 1.0/NVMe 1.2.1 specification.  The NVMf target exports NVMe
devices from a host machine over the network via RDMA.  Currently, the target is
limited to directly exporting physical NVMe devices, and the discovery subsystem
is not supported.

This release includes a general API cleanup, including renaming all declarations
in public headers to include a `spdk` prefix to prevent namespace clashes with
user code.

- NVMe
  - The `nvme_attach()` API was reworked into a new probe/attach model, which
  moves device detection into the NVMe library.  The new API also allows
  parallel initialization of NVMe controllers, providing a major reduction in
  startup time when using multiple controllers.
  - I/O queue allocation was changed to be explicit in the API.  Each function
  that generates I/O requests now takes a queue pair (`spdk_nvme_qpair *`)
  argument, and I/O queues may be allocated using
  `spdk_nvme_ctrlr_alloc_io_qpair()`.  This allows more flexible assignment of
  queue pairs than the previous model, which only allowed a single queue
  per thread and limited the total number of I/O queues to the lowest number
  supported on any attached controller.
  - Added support for the Write Zeroes command.
  - `examples/nvme/perf` can now report I/O command latency from the
   the controller's viewpoint using the Intel vendor-specific read/write latency
   log page.
  - Added namespace reservation command support, which can be used to coordinate
  sharing of a namespace between multiple hosts.
  - Added hardware SGL support, which enables use of scattered buffers that
   don't conform to the PRP list alignment and length requirements on supported
   NVMe controllers.
  - Added end-to-end data protection support, including the ability to write and
  read metadata in extended LBA (metadata appended to each block of data in the
  buffer) and separate metadata buffer modes.
  See `spdk_nvme_ns_cmd_write_with_md()` and `spdk_nvme_ns_cmd_read_with_md()`
  for details.
- IOAT
  - The DMA block fill feature is now exposed via the `ioat_submit_fill()`
  function.  This is functionally similar to `memset()`, except the memory is
  filled with an 8-byte repeating pattern instead of a single byte like memset.
- PCI
  - Added support for using DPDK for PCI device mapping in addition to the
  existing libpciaccess option.  Using the DPDK PCI support also allows use of
  the Linux VFIO driver model, which means that SPDK userspace drivers will work
  with the IOMMU enabled.  Additionally, SPDK applications may be run as an
  unprivileged user with access restricted to a specific set of PCIe devices.
  - The PCI library API was made more generic to abstract away differences
  between the underlying PCI access implementations.

v1.2.0: IOAT user-space driver
------------------------------

This release adds a user-space driver with support for the Intel I/O Acceleration Technology (I/OAT, also known as "Crystal Beach") DMA offload engine.

- IOAT
  - New user-space driver supporting DMA memory copy offload
  - Example programs `ioat/perf` and `ioat/verify`
  - Kernel-mode DMA engine test driver `kperf` for performance comparison
- NVMe
  - Per-I/O flags for Force Unit Access (FUA) and Limited Retry
  - Public API for retrieving log pages
  - Reservation register/acquire/release/report command support
  - Scattered payload support - an alternate API to provide I/O buffers via a sequence of callbacks
  - Declarations and `nvme/identify` support for Intel SSD DC P3700 series vendor-specific log pages and features
- Updated to support DPDK 2.2.0


v1.0.0: NVMe user-space driver
------------------------------

This is the initial open source release of the Storage Performance Development Kit (SPDK).

Features:
- NVMe user-space driver
- NVMe example programs
  - `examples/nvme/perf` tests performance (IOPS) using the NVMe user-space driver
  - `examples/nvme/identify` displays NVMe controller information in a human-readable format
- Linux and FreeBSD support