The NAPI budget (NAPI_POLL_WEIGHT), meaning the number of received packets that are allowed to be processed for each NAPI invocation, takes into consideration that each received packet is aimed for the kernel networking stack. That is not the case for the AF_XDP receive path, where the cost of each packet is significantly less. Therefore, this commit adds a new NAPI budget, which is the NAPI_POLL_WEIGHT scaled by 4. Typically that would be 256 in most configuration. It is encouraged that AF_XDP zero-copy capable drivers use the XSK_NAPI_WEIGHT, when zero-copy is enabled. Processing 256 packets targeted for AF_XDP is still less work than 64 (NAPI_POLL_WEIGHT) packets going to the kernel networking stack. Jakub suggested in [1] that a more generic approach was preferred over "driver hacks". It is arguable if adding the budget as a define which is a scaled NAPI_POLL_WEIGHT would classify as "generic", but it is a bit further away from "driver hacks". ;-) The first patch adds the actual define, and last three make the Intel drivers use it. The AF_XDP Rx performance for "rxdrop" is up ~8% on my machine. Routing this series via bpf-next instead of Intel Wired/netdev, since it is a core AF_XDP addition, and hopefully Nvidia will pick this up for the mlx5 driver. Björn [1] https://lore.kernel.org/netdev/20200728131512.17c41621@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ Björn Töpel (4): xsk: add XSK_NAPI_WEIGHT define i40e, xsk: use XSK_NAPI_WEIGHT as NAPI poll budget ice, xsk: use XSK_NAPI_WEIGHT as NAPI poll budget ixgbe, xsk: use XSK_NAPI_WEIGHT as NAPI poll budget drivers/net/ethernet/intel/i40e/i40e_xsk.c | 2 +- drivers/net/ethernet/intel/ice/ice_xsk.c | 2 +- drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 2 +- include/net/xdp_sock_drv.h | 3 +++ 4 files changed, 6 insertions(+), 3 deletions(-) base-commit: bc0b5a03079bd78fb3d5cba1ccabf0a7efb1d99f -- 2.25.1
