This series addresses a problem that arises when AF_XDP zero-copy is enabled, and the kernel softirq Rx processing and userland process is running on the same core. In contrast to the two-core case, when the userland process/Rx softirq shares one core, it it very important that the kernel is not doing unnecessary work, but instead let the userland process run. This has not been the case. For the Intel drivers, when the XDP_REDIRECT fails due to a full Rx ring, the NAPI loop will simply drop the packet and continue processing the next packet. The XDP_REDIRECT operation will then fail again, since userland has not been able to empty the full Rx ring. The fix for this is letting the NAPI loop exit early, if the AF_XDP socket Rx ring is full. The outline is as following; The first patch cleans up the error codes returned by xdp_do_redirect(), so that a driver can figure out when the Rx ring is full (ENOBUFS). Patch two adds an extended xdp_do_redirect() variant that returns what kind of map that was used in the XDP_REDIRECT action. The third patch adds an AF_XDP driver helper to figure out if the Rx ring was full. Finally, the last three patches implements the "early exit" support for Intel. On my machine the "one core scenario Rx drop" performance went from ~65Kpps to 21Mpps. In other words, from "not usable" to "usable". YMMV. I prefer to route this series via bpf-next, since it include core changes, and not only driver changes. Have a nice weekend! Björn Björn Töpel (6): xsk: improve xdp_do_redirect() error codes xdp: introduce xdp_do_redirect_ext() function xsk: introduce xsk_do_redirect_rx_full() helper i40e, xsk: finish napi loop if AF_XDP Rx queue is full ice, xsk: finish napi loop if AF_XDP Rx queue is full ixgbe, xsk: finish napi loop if AF_XDP Rx queue is full drivers/net/ethernet/intel/i40e/i40e_xsk.c | 23 ++++++++++++++------ drivers/net/ethernet/intel/ice/ice_xsk.c | 23 ++++++++++++++------ drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 23 ++++++++++++++------ include/linux/filter.h | 2 ++ include/net/xdp_sock_drv.h | 9 ++++++++ net/core/filter.c | 16 ++++++++++++-- net/xdp/xsk.c | 2 +- net/xdp/xsk_queue.h | 2 +- 8 files changed, 75 insertions(+), 25 deletions(-) base-commit: 8eb629585d2231e90112148009e2a11b0979ca38 -- 2.25.1
