RE: [PATCH bpf-next v5 00/15] Introduce AF_XDP buffer allocation API

["Kirsher, Jeffrey T" <jeffrey.t.kirsher@intel.com>]

> -----Original Message-----
> From: Björn Töpel <bjorn.topel@gmail.com>
> Sent: Wednesday, May 20, 2020 12:21
> To: ast@kernel.org; daniel@iogearbox.net; davem@davemloft.net;
> kuba@kernel.org; hawk@kernel.org; john.fastabend@gmail.com;
> netdev@vger.kernel.org; bpf@vger.kernel.org; Karlsson, Magnus
> <magnus.karlsson@intel.com>; jonathan.lemon@gmail.com; Kirsher, Jeffrey T
> <jeffrey.t.kirsher@intel.com>
> Cc: Björn Töpel <bjorn.topel@gmail.com>; maximmi@mellanox.com;
> Fijalkowski, Maciej <maciej.fijalkowski@intel.com>; Topel, Bjorn
> <bjorn.topel@intel.com>
> Subject: [PATCH bpf-next v5 00/15] Introduce AF_XDP buffer allocation API
> 
> Overview
> ========
> 
> Driver adoption for AF_XDP has been slow. The amount of code required to
> proper support AF_XDP is substantial and the driver/core APIs are vague or
> even non-existing. Drivers have to manually adjust data offsets, updating
> AF_XDP handles differently for different modes (aligned/unaligned).
> 
> This series attempts to improve the situation by introducing an AF_XDP buffer
> allocation API. The implementation is based on a single core (single
> producer/consumer) buffer pool for the AF_XDP UMEM.
> 
> A buffer is allocated using the xsk_buff_alloc() function, and returned using
> xsk_buff_free(). If a buffer is disassociated with the pool, e.g. when a buffer is
> passed to an AF_XDP socket, a buffer is said to be released. Currently, the
> release function is only used by the AF_XDP internals and not visible to the
> driver.
> 
> Drivers using this API should register the XDP memory model with the new
> MEM_TYPE_XSK_BUFF_POOL type, which will supersede the
> MEM_TYPE_ZERO_COPY type.
> 
> The buffer type is struct xdp_buff, and follows the lifetime of regular xdp_buffs,
> i.e.  the lifetime of an xdp_buff is restricted to a NAPI context. In other words,
> the API is not replacing xdp_frames.
> 
> DMA mapping/synching is folded into the buffer handling as well.
> 
> @JeffK The Intel drivers changes should go through the bpf-next tree,
>        and not your regular Intel tree, since multiple (non-Intel)
>        drivers are affected.
[Kirsher, Jeffrey T] 

Yep, I am fine with that.  Fortunately the changes are confined to the *_xsk files, which do not affect anything in my queue of driver changes.  I usually let you handle all BPF related changes and just set your patches to "Awaiting Upstream" when they come across IWL mailing list.  Thank you for CC the IWL list, that way I am aware.

> 
> The outline of the series is as following:
> 
> Patch 1 is a fix for xsk_umem_xdp_frame_sz().
> 
> Patch 2 to 4 are restructures/clean ups. The XSKMAP implementation is moved
> to net/xdp/. Functions/defines/enums that are only used by the AF_XDP
> internals are moved from the global include/net/xdp_sock.h to net/xdp/xsk.h.
> We are also introducing a new "driver include file", include/net/xdp_sock_drv.h,
> which is the only file NIC driver developers adding AF_XDP zero-copy support
> should care about.
> 
> Patch 5 adds the new API, and migrates the "copy-mode"/skb-mode AF_XDP
> path to the new API.
> 
> Patch 6 to 11 migrates the existing zero-copy drivers to the new API.
> 
> Patch 12 removes the MEM_TYPE_ZERO_COPY memory type, and the "handle"
> member of struct xdp_buff.
> 
> Patch 13 simplifies the xdp_return_{frame,frame_rx_napi,buff}
> functions.
> 
> Patch 14 is a performance patch, where some functions are inlined.
> 
> Finally, patch 15 updates the MAINTAINERS file to correctly mirror the new file
> layout.
> 
> Note that this series removes the "handle" member from struct xdp_buff, which
> reduces the xdp_buff size.
> 
> After this series, the diff stat of drivers/net/ is:
>   27 files changed, 419 insertions(+), 1288 deletions(-)
> 
> This series is a first step of simplifying the driver side of AF_XDP. I think more
> of the AF_XDP logic can be moved from the drivers to the AF_XDP core, e.g.
> the "need wakeup" set/clear functionality.
> 
> Statistics when allocation fails can now be added to the socket statistics via the
> XDP_STATISTICS getsockopt(). This will be added in a follow up series.
> 
> 
> Performance
> ===========
> 
> As a nice side effect, performance is up a bit as well.
> 
>   * i40e: 3% higher pps for rxdrop, zero-copy, aligned and unaligned
>     (40 GbE, 64B packets).
>   * mlx5: RX +0.8 Mpps, TX +0.4 Mpps
> 
> 
> Changelog
> =========
> 
> v4->v5:
>   * Fix various kdoc and GCC warnings (W=1). (Jakub)
> 
> v3->v4:
>     * mlx5: Remove unused variable num_xsk_frames. (Jakub)
>     * i40e: Made i40e_fd_handle_status() static. (kbuild test robot)
> 
> v2->v3:
>   * Added xsk_umem_xdp_frame_sz() fix to the series. (Björn)
>   * Initialize struct xdp_buff member frame_sz. (Björn)
>   * Add API to query the DMA address of a frame. (Maxim)
>   * Do DMA sync for CPU till the end of the frame to handle possible
>     growth (frame_sz). (Maxim)
>   * mlx5: Handle frame_sz, use xsk_buff_xdp_get_frame_dma, use
>     xsk_buff API for DMA sync on TX, add performance numbers. (Maxim)
> 
> v1->v2:
>   * mlx5: Fix DMA address handling, set XDP metadata to invalid. (Maxim)
>   * ixgbe: Fixed xdp_buff data_end update. (Björn)
>   * Swapped SoBs in patch 4. (Maxim)
> 
> rfc->v1:
>   * Fixed build errors/warnings for m68k and riscv. (kbuild test
>     robot)
>   * Added headroom/chunk size getter. (Maxim/Björn)
>   * mlx5: Put back the sanity check for XSK params, use XSK API to get
>     the total headroom size. (Maxim)
>   * Fixed spelling in commit message. (Björn)
>   * Make sure xp_validate_desc() is inlined for Tx perf. (Maxim)
>   * Sorted file entries. (Joe)
>   * Added xdp_return_{frame,frame_rx_napi,buff} simplification (Björn)
> 
> Thanks for all the comments/input/help!
> 
> 
> Cheers,
> Björn
> 
> Björn Töpel (14):
>   xsk: fix xsk_umem_xdp_frame_sz()
>   xsk: move xskmap.c to net/xdp/
>   xsk: move defines only used by AF_XDP internals to xsk.h
>   xsk: introduce AF_XDP buffer allocation API
>   i40e: refactor rx_bi accesses
>   i40e: separate kernel allocated rx_bi rings from AF_XDP rings
>   i40e, xsk: migrate to new MEM_TYPE_XSK_BUFF_POOL
>   ice, xsk: migrate to new MEM_TYPE_XSK_BUFF_POOL
>   ixgbe, xsk: migrate to new MEM_TYPE_XSK_BUFF_POOL
>   mlx5, xsk: migrate to new MEM_TYPE_XSK_BUFF_POOL
>   xsk: remove MEM_TYPE_ZERO_COPY and corresponding code
>   xdp: simplify xdp_return_{frame,frame_rx_napi,buff}
>   xsk: explicitly inline functions and move definitions
>   MAINTAINERS, xsk: update AF_XDP section after moves/adds
> 
> Magnus Karlsson (1):
>   xsk: move driver interface to xdp_sock_drv.h
> 
>  MAINTAINERS                                   |   6 +-
>  drivers/net/ethernet/intel/i40e/i40e_main.c   |  28 +-
>  drivers/net/ethernet/intel/i40e/i40e_txrx.c   | 134 +++----
>  drivers/net/ethernet/intel/i40e/i40e_txrx.h   |  17 +-
>  .../ethernet/intel/i40e/i40e_txrx_common.h    |  40 +-
>  drivers/net/ethernet/intel/i40e/i40e_type.h   |   5 +-
>  drivers/net/ethernet/intel/i40e/i40e_xsk.c    | 379 +++---------------
>  drivers/net/ethernet/intel/i40e/i40e_xsk.h    |   3 +-
>  drivers/net/ethernet/intel/ice/ice_base.c     |  16 +-
>  drivers/net/ethernet/intel/ice/ice_txrx.h     |   8 +-
>  drivers/net/ethernet/intel/ice/ice_xsk.c      | 378 ++---------------
>  drivers/net/ethernet/intel/ice/ice_xsk.h      |  13 +-
>  drivers/net/ethernet/intel/ixgbe/ixgbe.h      |   9 +-
>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |  15 +-
>  .../ethernet/intel/ixgbe/ixgbe_txrx_common.h  |   2 +-
>  drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c  | 309 +++-----------
>  drivers/net/ethernet/mellanox/mlx5/core/en.h  |   7 +-
>  .../ethernet/mellanox/mlx5/core/en/params.c   |  13 +-
>  .../net/ethernet/mellanox/mlx5/core/en/xdp.c  |  33 +-
>  .../net/ethernet/mellanox/mlx5/core/en/xdp.h  |   2 +-
>  .../ethernet/mellanox/mlx5/core/en/xsk/rx.c   | 113 +-----
>  .../ethernet/mellanox/mlx5/core/en/xsk/rx.h   |  25 +-
>  .../ethernet/mellanox/mlx5/core/en/xsk/tx.c   |   9 +-
>  .../ethernet/mellanox/mlx5/core/en/xsk/tx.h   |   2 +-
>  .../ethernet/mellanox/mlx5/core/en/xsk/umem.c |  51 +--
> .../net/ethernet/mellanox/mlx5/core/en_main.c |  25 +-
>  .../net/ethernet/mellanox/mlx5/core/en_rx.c   |  34 +-
>  drivers/net/hyperv/netvsc_bpf.c               |   1 -
>  include/net/xdp.h                             |   9 +-
>  include/net/xdp_sock.h                        | 287 +------------
>  include/net/xdp_sock_drv.h                    | 232 +++++++++++
>  include/net/xsk_buff_pool.h                   | 140 +++++++
>  include/trace/events/xdp.h                    |   2 +-
>  kernel/bpf/Makefile                           |   3 -
>  net/core/xdp.c                                |  51 +--
>  net/ethtool/channels.c                        |   2 +-
>  net/ethtool/ioctl.c                           |   2 +-
>  net/xdp/Makefile                              |   3 +-
>  net/xdp/xdp_umem.c                            |  55 +--
>  net/xdp/xdp_umem.h                            |   2 +-
>  net/xdp/xsk.c                                 | 204 ++++------
>  net/xdp/xsk.h                                 |  30 ++
>  net/xdp/xsk_buff_pool.c                       | 336 ++++++++++++++++
>  net/xdp/xsk_diag.c                            |   2 +-
>  net/xdp/xsk_queue.c                           |  63 +--
>  net/xdp/xsk_queue.h                           | 117 ++----
>  {kernel/bpf => net/xdp}/xskmap.c              |   2 +
>  47 files changed, 1279 insertions(+), 1940 deletions(-)  create mode 100644
> include/net/xdp_sock_drv.h  create mode 100644 include/net/xsk_buff_pool.h
> create mode 100644 net/xdp/xsk_buff_pool.c  rename {kernel/bpf =>
> net/xdp}/xskmap.c (99%)
> 
> 
> base-commit: dda18a5c0b75461d1ed228f80b59c67434b8d601
> --
> 2.25.1