[PATCH v8 0/5] vhost: support async dequeue data path

[Maxime Coquelin]

On 5/16/22 13:10, xuan.ding at intel.com wrote:
> From: Xuan Ding <xuan.ding at intel.com>
> 
> The presence of asynchronous path allows applications to offload memory
> copies to DMA engine, so as to save CPU cycles and improve the copy
> performance. This patch set implements vhost async dequeue data path
> for split ring. The code is based on latest enqueue changes [1].
> 
> This patch set is a new design and implementation of [2]. Since dmadev
> was introduced in DPDK 21.11, to simplify application logics, this patch
> integrates dmadev in vhost. With dmadev integrated, vhost supports M:N
> mapping between vrings and DMA virtual channels. Specifically, one vring
> can use multiple different DMA channels and one DMA channel can be
> shared by multiple vrings at the same time.
> 
> A new asynchronous dequeue function is introduced:
>          1) rte_vhost_async_try_dequeue_burst(int vid, uint16_t queue_id,
>                  struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts,
>                  uint16_t count, int *nr_inflight,
>                  uint16_t dma_id, uint16_t vchan_id)
> 
>          Receive packets from the guest and offloads copies to DMA
> virtual channel.
> 
> [1] https://mails.dpdk.org/archives/dev/2022-February/234555.html
> [2] https://mails.dpdk.org/archives/dev/2021-September/218591.html
> 
> v7->v8:
> * change dma_id to int16_t
> * refine API documentation
> 
> v6->v7:
> * correct code formatting
> * change some functions to inline
> 
> v5->v6:
> * adjust EXPERIMENTAL header
> 
> v4->v5:
> * rebase to latest DPDK
> * add some checks
> 
> v3->v4:
> * fix CI build warnings
> * adjust some indentation
> * pass vq instead of queue_id
> 
> v2->v3:
> * fix mbuf not updated correctly for large packets
> 
> v1->v2:
> * fix a typo
> * fix a bug in desc_to_mbuf filling
> 
> RFC v3 -> v1:
> * add sync and async path descriptor to mbuf refactoring
> * add API description in docs
> 
> RFC v2 -> RFC v3:
> * rebase to latest DPDK version
> 
> RFC v1 -> RFC v2:
> * fix one bug in example
> * rename vchan to vchan_id
> * check if dma_id and vchan_id valid
> * rework all the logs to new standard
> 
> Xuan Ding (5):
>    vhost: prepare sync for descriptor to mbuf refactoring
>    vhost: prepare async for descriptor to mbuf refactoring
>    vhost: merge sync and async descriptor to mbuf filling
>    vhost: support async dequeue for split ring
>    examples/vhost: support async dequeue data path
> 
>   doc/guides/prog_guide/vhost_lib.rst    |   6 +
>   doc/guides/rel_notes/release_22_07.rst |   5 +
>   doc/guides/sample_app_ug/vhost.rst     |   9 +-
>   examples/vhost/main.c                  | 286 ++++++++++-----
>   examples/vhost/main.h                  |  32 +-
>   examples/vhost/virtio_net.c            |  16 +-
>   lib/vhost/rte_vhost_async.h            |  37 ++
>   lib/vhost/version.map                  |   2 +-
>   lib/vhost/vhost.h                      |   1 +
>   lib/vhost/virtio_net.c                 | 473 ++++++++++++++++++++++---
>   10 files changed, 715 insertions(+), 152 deletions(-)
> 

Applied to dpdk-next-virtio/main.

Thanks,
Maxime