netdev - [PATCH net 00/15] netpoll: avoid capture effects for NAPI drivers

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Date:   Fri, 21 Sep 2018 15:27:37 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Michael Chan <michael.chan@...adcom.com>,
        Ariel Elior <ariel.elior@...ium.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Tariq Toukan <tariqt@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Song Liu <songliubraving@...com>,
        Jay Vosburgh <j.vosburgh@...il.com>,
        Veaceslav Falico <vfalico@...il.com>,
        Andy Gospodarek <andy@...yhouse.net>
Subject: [PATCH net 00/15] netpoll: avoid capture effects for NAPI drivers

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