Hello everyone,I'm not able to make AF_XDP busy polling work correctly on a ConnectX-4 NIC. Whenever I run the xdpsock application in busy polling mode (-B flag), in either l2fwd or rx-drop mode, the NIC keeps generating interrupts and processing rate is very low. I'm on kernel 5.13.
Is this a known problem?By looking at the code I might have a possible explanation for this behavior: - To perform a busy loop on the socket, a valid napi id must be stored in the sk_napi_id field of the socket structure (https://elixir.bootlin.com/linux/latest/source/include/net/busy_poll.h#L109) - The sk_napi_id field of the socket is populated when the first packet is redirected to the socket, and the value is taken from the rxq associated to the packet xdp_buff (https://elixir.bootlin.com/linux/latest/source/include/net/busy_poll.h#L173) - mlx5 appears to always assign the napi_id 0 to xsk queues, that is not a valid napi_id (https://elixir.bootlin.com/linux/latest/source/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c#L74)
Does this make sense? Thank you, Federico
|