On Tue, Jul 16, 2024 at 2:46 PM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote: > > ## AF_XDP > > XDP socket(AF_XDP) is an excellent bypass kernel network framework. The zero > copy feature of xsk (XDP socket) needs to be supported by the driver. The > performance of zero copy is very good. mlx5 and intel ixgbe already support > this feature, This patch set allows virtio-net to support xsk's zerocopy xmit > feature. > > At present, we have completed some preparation: > > 1. vq-reset (virtio spec and kernel code) > 2. virtio-core premapped dma > 3. virtio-net xdp refactor > > So it is time for Virtio-Net to complete the support for the XDP Socket > Zerocopy. > > Virtio-net can not increase the queue num at will, so xsk shares the queue with > kernel. > > This patch set includes some refactor to the virtio-net to let that to support > AF_XDP. > > ## About virtio premapped mode > > The current configuration sets the virtqueue (vq) to premapped mode, > implying that all buffers submitted to this queue must be mapped ahead > of time. This presents a challenge for the virtnet send queue (sq): the > virtnet driver would be required to keep track of dma information for vq > size * 17, which can be substantial. However, if the premapped mode were > applied on a per-buffer basis, the complexity would be greatly reduced. > With AF_XDP enabled, AF_XDP buffers would become premapped, while kernel > skb buffers could remain unmapped. > > We can distinguish them by sg_page(sg), When sg_page(sg) is NULL, this > indicates that the driver has performed DMA mapping in advance, allowing > the Virtio core to directly utilize sg_dma_address(sg) without > conducting any internal DMA mapping. Additionally, DMA unmap operations > for this buffer will be bypassed. > > ## performance > > ENV: Qemu with vhost-user(polling mode). > Host CPU: Intel(R) Xeon(R) Platinum 8163 CPU @ 2.50GHz > > ### virtio PMD in guest with testpmd > > testpmd> show port stats all > > ######################## NIC statistics for port 0 ######################## > RX-packets: 19531092064 RX-missed: 0 RX-bytes: 1093741155584 > RX-errors: 0 > RX-nombuf: 0 > TX-packets: 5959955552 TX-errors: 0 TX-bytes: 371030645664 > > > Throughput (since last show) > Rx-pps: 8861574 Rx-bps: 3969985208 > Tx-pps: 8861493 Tx-bps: 3969962736 > ############################################################################ > > ### AF_XDP PMD in guest with testpmd > > testpmd> show port stats all > > ######################## NIC statistics for port 0 ######################## > RX-packets: 68152727 RX-missed: 0 RX-bytes: 3816552712 > RX-errors: 0 > RX-nombuf: 0 > TX-packets: 68114967 TX-errors: 33216 TX-bytes: 3814438152 > > Throughput (since last show) > Rx-pps: 6333196 Rx-bps: 2837272088 > Tx-pps: 6333227 Tx-bps: 2837285936 > ############################################################################ > > But AF_XDP consumes more CPU for tx and rx napi(100% and 86%). > > Please review. > > Thanks. > > Xuan Zhuo (13): > virtio_ring: introduce vring_need_unmap_buffer > virtio_ring: split: harden dma unmap for indirect > virtio_ring: packed: harden dma unmap for indirect > virtio_ring: perform premapped operations based on per-buffer > virtio-net: rq submits premapped buffer per buffer > virtio_ring: remove API virtqueue_set_dma_premapped > virtio_net: refactor the xmit type > virtio_net: xsk: bind/unbind xsk for tx > virtio_net: xsk: prevent disable tx napi > virtio_net: xsk: tx: support xmit xsk buffer > virtio_net: xsk: tx: handle the transmitted xsk buffer > virtio_net: update tx timeout record > virtio_net: xdp_features add NETDEV_XDP_ACT_XSK_ZEROCOPY > > drivers/net/virtio_net.c | 363 ++++++++++++++++++++++++++++------- > drivers/virtio/virtio_ring.c | 302 ++++++++++++----------------- > include/linux/virtio.h | 2 - > 3 files changed, 421 insertions(+), 246 deletions(-) > > -- > 2.32.0.3.g01195cf9f > Hi Xuan: I wonder why this series is tagged as "RFC"? Thanks
