5. NVIDIA MLX5 vDPA Driver


NVIDIA acquired Mellanox Technologies in 2020. The DPDK documentation and code might still include instances of or references to Mellanox trademarks (like BlueField and ConnectX) that are now NVIDIA trademarks.

The mlx5 vDPA (vhost data path acceleration) driver library (librte_vdpa_mlx5) provides support for NVIDIA ConnectX-6, NVIDIA ConnectX-6 Dx, NVIDIA ConnectX-6 Lx, NVIDIA ConnectX7, NVIDIA BlueField, NVIDIA BlueField-2 and NVIDIA BlueField-3 families of 10/25/40/50/100/200 Gb/s adapters as well as their virtual functions (VF) in SR-IOV context.


This driver is enabled automatically when using “meson” build system which will detect dependencies.

See NVIDIA MLX5 Common Driver guide for design details, and which PMDs can be combined with vDPA PMD.

5.1. Supported NICs

  • NVIDIA® ConnectX®-6 200G MCX654106A-HCAT (2x200G)
  • NVIDIA® ConnectX®-6 Dx EN 25G MCX621102AN-ADAT (2x25G)
  • NVIDIA® ConnectX®-6 Dx EN 100G MCX623106AN-CDAT (2x100G)
  • NVIDIA® ConnectX®-6 Dx EN 200G MCX623105AN-VDAT (1x200G)
  • NVIDIA® ConnectX®-6 Lx EN 25G MCX631102AN-ADAT (2x25G)
  • NVIDIA® ConnectX®-7 200G CX713106AE-HEA_QP1_Ax (2x200G)
  • NVIDIA® BlueField SmartNIC 25G MBF1M332A-ASCAT (2x25G)
  • NVIDIA® BlueField ®-2 SmartNIC MT41686 - MBF2H332A-AEEOT_A1 (2x25G)
  • NVIDIA® BlueField®-3 200GbE 900-9D3B6-00CV-AAB_Ax

5.2. Prerequisites

5.2.1. Run-time configuration Driver options

Please refer to mlx5 common options for an additional list of options shared with other mlx5 drivers.

  • event_mode parameter [int]

    • 0, Completion queue scheduling will be managed by a timer thread which automatically adjusts its delays to the coming traffic rate.
    • 1, Completion queue scheduling will be managed by a timer thread with fixed delay time.
    • 2, Completion queue scheduling will be managed by interrupts. Each CQ burst arms the CQ in order to get an interrupt event in the next traffic burst.
    • Default mode is 1.
  • event_us parameter [int]

    Per mode micro-seconds parameter - relevant only for event mode 0 and 1:

    • 0, A nonzero value to set timer step in micro-seconds. The timer thread dynamic delay change steps according to this value. Default value is 1us.
    • 1, A value to set fixed timer delay in micro-seconds. Default value is 0us.
  • no_traffic_time parameter [int]

    A nonzero value defines the traffic off time, in polling cycle time units, that moves the driver to no-traffic mode. In this mode the polling is stopped and interrupts are configured to the device in order to notify traffic for the driver. Default value is 16.

  • event_core parameter [int]

    The CPU core number of the timer thread, default: EAL main lcore.


This core can be shared among different mlx5 vDPA devices as event_core but using it also for other tasks may affect the performance and the latency of the mlx5 vDPA devices.

  • max_conf_threads parameter [int]

    Allow the driver to use internal threads to obtain fast configuration. All the threads will be open on the same core of the event completion queue scheduling thread.

    • 0, default, don’t use internal threads for configuration.
    • 1 - 256, number of internal threads in addition to the caller thread (8 is suggested). This value, if not 0, should be the same for all the devices; the first probing will take it with the event_core for all the multi-thread configurations in the driver.
  • hw_latency_mode parameter [int]

    The completion queue moderation mode:

    • 0, HW default.
    • 1, Latency is counted from the first packet completion report.
    • 2, Latency is counted from the last packet completion.
  • hw_max_latency_us parameter [int]

    • 1 - 4095, The maximum time in microseconds that packet completion report can be delayed.
    • 0, HW default.
  • hw_max_pending_comp parameter [int]

    • 1 - 65535, The maximum number of pending packets completions in an HW queue.
    • 0, HW default.
  • queue_size parameter [int]

    • 1 - 1024, Virtio queue depth for pre-creating queue resource to speed up first time queue creation. Set it together with queues parameter.
    • 0, default value, no pre-create virtq resource.
  • queues parameter [int]

    • 1 - 128, Maximum number of virtio queue pair (including 1 Rx queue and 1 Tx queue) for pre-creating queue resource to speed up first time queue creation. Set it together with queue_size parameter.
    • 0, default value, no pre-create virtq resource. Error handling

Upon potential hardware errors, mlx5 PMD try to recover, give up if failed 3 times in 3 seconds, virtq will be put in disable state. User should check log to get error information, or query vdpa statistics counter to know error type and count report. Statistics

The device statistics counter persists in reconfiguration until the device gets removed. User can reset counters by calling function rte_vdpa_reset_stats().