This is the second part of virtio-net support AF_XDP zero copy. The whole patch set http://lore.kernel.org/all/20231229073108.57778-1-xuanzhuo@xxxxxxxxxxxxxxxxx ## About the branch This patch set is pushed to the net-next branch, but some patches are about virtio core. Because the entire patch set for virtio-net to support AF_XDP should be pushed to net-next, I hope these patches will be merged into net-next with the virtio core maintains's Acked-by. ============================================================================ ## 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. On the other hand, Virtio-Net does not support generate interrupt from driver manually, so when we wakeup tx xmit, we used some tips. If the CPU run by TX NAPI last time is other CPUs, use IPI to wake up NAPI on the remote CPU. If it is also the local CPU, then we wake up napi directly. This patch set includes some refactor to the virtio-net to let that to support AF_XDP. ## 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%). ## maintain I am currently a reviewer for virtio-net. I commit to maintain AF_XDP support in virtio-net. Please review. Thanks. Xuan Zhuo (5): virtio_ring: introduce virtqueue_get_buf_ctx_dma() virtio_ring: virtqueue_disable_and_recycle let the callback detach bufs virtio_ring: introduce virtqueue_detach_unused_buf_dma() virtio_ring: introduce virtqueue_get_dma_premapped() virtio_net: sq support premapped mode drivers/net/virtio/main.c | 177 ++++++++++++++++++------ drivers/net/virtio/virtio_net.h | 13 +- drivers/virtio/virtio_ring.c | 235 ++++++++++++++++++++++++-------- include/linux/virtio.h | 22 ++- 4 files changed, 340 insertions(+), 107 deletions(-) -- 2.32.0.3.g01195cf9f
