Now, some drivers support the zero-copy feature of AF_XDP sockets, which can significantly reduce CPU utilization for XDP programs.
This patch set enables tun to also support the AF_XDP Rx zero-copy feature, with the following changes: 1. The unnecessary 'dma_page' check has been removed when binding the AF_XDP socket to the device, as it is not needed for the vNIC. 2. A check has been added when consuming the buffer in vhost_net_buf_produce(), as the vq's rx_array may be empty after AF_XDP Rx zero-copy is enabled. 3. The peek_len function is now used to consume a xsk->desc and retrieve its length. 4. AF_XDP Rx zero-copy support has been added for tun. This patchset is based on Linux 6.4.0+(openEuler 23.09) and has successfully passed Netperf and Netserver stress testing with multiple streams between VM A and VM B, using AF_XDP and OVS. With this patch applied, the system CPU usage for OVS' PMD has decreased from 59.8% to 8.8% while forwarding 700000pps. Yunjian Wang (2): xsk: Remove non-zero 'dma_page' check in xp_assign_dev tun: AF_XDP Rx zero-copy support drivers/net/tun.c | 165 +++++++++++++++++++++++++++++++++++++++- drivers/vhost/net.c | 18 +++-- net/xdp/xsk_buff_pool.c | 7 -- 3 files changed, 176 insertions(+), 14 deletions(-) -- 2.33.0
