As diagnosed by Song Liu, ndo_poll_controller() can be very dangerous on loaded hosts, since the cpu calling ndo_poll_controller() might steal all NAPI contexts (for all RX/TX queues of the NIC).
This capture, showing one ksoftirqd eating all cycles can last for unlimited amount of time, since one cpu is generally not able to drain all the queues under load. It seems that all networking drivers that do use NAPI for their TX completions, should not provide a ndo_poll_controller() : Most NAPI drivers have netpoll support already handled in core networking stack, since netpoll_poll_dev() uses poll_napi(dev) to iterate through registered NAPI contexts for a device. This patch series take care of the first round, we will handle other drivers in future rounds. Eric Dumazet (15): netpoll: make ndo_poll_controller() optional bonding: use netpoll_poll_dev() helper ixgbe: remove ndo_poll_controller ixgbevf: remove ndo_poll_controller fm10k: remove ndo_poll_controller ixgb: remove ndo_poll_controller igb: remove ndo_poll_controller ice: remove ndo_poll_controller i40evf: remove ndo_poll_controller mlx4: remove ndo_poll_controller mlx5: remove ndo_poll_controller bnx2x: remove ndo_poll_controller bnxt: remove ndo_poll_controller nfp: remove ndo_poll_controller tun: remove ndo_poll_controller drivers/net/bonding/bond_main.c | 11 +---- .../net/ethernet/broadcom/bnx2x/bnx2x_main.c | 16 ------- drivers/net/ethernet/broadcom/bnxt/bnxt.c | 18 -------- drivers/net/ethernet/intel/fm10k/fm10k.h | 3 -- .../net/ethernet/intel/fm10k/fm10k_netdev.c | 3 -- drivers/net/ethernet/intel/fm10k/fm10k_pci.c | 22 ---------- .../net/ethernet/intel/i40evf/i40evf_main.c | 26 ----------- drivers/net/ethernet/intel/ice/ice_main.c | 27 ------------ drivers/net/ethernet/intel/igb/igb_main.c | 30 ------------- drivers/net/ethernet/intel/ixgb/ixgb_main.c | 25 ----------- drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 25 ----------- .../net/ethernet/intel/ixgbevf/ixgbevf_main.c | 21 --------- .../net/ethernet/mellanox/mlx4/en_netdev.c | 20 --------- .../net/ethernet/mellanox/mlx5/core/en_main.c | 19 -------- .../ethernet/netronome/nfp/nfp_net_common.c | 18 -------- drivers/net/tun.c | 43 ------------------- include/linux/netpoll.h | 5 ++- net/core/netpoll.c | 19 +++----- 18 files changed, 12 insertions(+), 339 deletions(-) -- 2.19.0.444.g18242da7ef-goog
