[dpdk-dev] [PATCH v2 0/8] support VIRTIO_F_IN_ORDER feature

[Marvin Liu <yong.liu@intel.com>]

In latest virtio-spec, new feature bit VIRTIO_F_IN_ORDER was introduced.
When this feature has been negotiated, virtio driver will use
descriptors in ring order: starting from offset 0 in the table, and
wrapping around at the end of the table. Vhost devices will always use
descriptors in the same order in which they have been made available.
This can reduce virtio accesses to used ring.

Based on updated virtio-spec, this series realized IN_ORDER prototype
in virtio driver. Due to new [RT]x path added into selection, also add
two new parameters mrg_rx and in_order into virtio-user vdev parameters
list. This will allow user to configure feature bits thus can impact
[RT]x path selection.

Performance of virtio user with IN_ORDER feature:

    Platform: Purely
    CPU: Intel(R) Xeon(R) Platinum 8160 CPU @ 2.10GHz
    DPDK baseline: 18.05
    Setup: testpmd with vhost vdev + testpmd with virtio vdev

    +--------------+----------+----------+---------+
    |Vhost->Virtio |1 Queue   |2 Queues  |4 Queues |
    +--------------+----------+----------+---------+
    |Inorder       |12.0Mpps  |24.2Mpps  |26.0Mpps |
    |Normal        |12.1Mpps  |18.5Mpps  |18.9Mpps |
    +--------------+----------+----------+---------+
    
    +--------------+----------+----------------+---------+
    |Virtio->Vhost |1 Queue   |2 Queues        |4 Queues |
    +--------------+----------+----------------+---------+
    |Inorder       |13.8Mpps  |10.7 ~ 15.2Mpps |11.5Mpps |
    |Normal        |13.3Mpps  |9.8 ~ 14Mpps    |10.5Mpps |
    +--------------+----------+----------------+---------+
    
    +---------+----------+----------------+----------------+
    |Loopback |1 Queue   |2 Queues        |4 Queues        |
    +---------+----------+----------------+----------------+
    |Inorder  |7.4Mpps   |9.1 ~ 11.6Mpps  |10.5 ~ 11.3Mpps |
    +---------+----------+----------------+----------------+
    |Normal   |7.5Mpps   |7.7 ~ 9.0Mpps   |7.6 ~ 7.8Mpps   |
    +---------+----------+----------------+----------------+

v2:
- merge to latest dpdk-net-virtio 
- not use in_direct for normal xmit packets
- update available ring for each descriptor
- clean up IN_ORDER xmit function
- unmask feature bits when disabled in_order or mgr_rxbuf
- extract common part between IN_ORDER and normal functions
- update performance result

Marvin Liu (8):
  vhost: announce VIRTIO_F_IN_ORDER support
  net/virtio: add VIRTIO_F_IN_ORDER definition
  net/virtio-user: add mrg_rxbuf and in_order vdev parameters
  net/virtio: free IN_ORDER descriptors before device start
  net/virtio: extract common part for IN_ORDER functions
  net/virtio: support IN_ORDER Rx and Tx
  net/virtio: add IN_ORDER Rx/Tx into selection
  net/virtio: annouce VIRTIO_F_IN_ORDER support

 drivers/net/virtio/virtio_ethdev.c            |  31 +-
 drivers/net/virtio/virtio_ethdev.h            |   7 +
 drivers/net/virtio/virtio_pci.h               |   8 +
 drivers/net/virtio/virtio_rxtx.c              | 635 ++++++++++++++++--
 .../net/virtio/virtio_user/virtio_user_dev.c  |  14 +-
 .../net/virtio/virtio_user/virtio_user_dev.h  |   3 +-
 drivers/net/virtio/virtio_user_ethdev.c       |  33 +-
 drivers/net/virtio/virtqueue.c                |   8 +
 drivers/net/virtio/virtqueue.h                |   2 +
 lib/librte_vhost/socket.c                     |   6 +
 lib/librte_vhost/vhost.h                      |  10 +-
 11 files changed, 688 insertions(+), 69 deletions(-)

-- 
2.17.0