[PATCH iwl-next v4 0/4] igb: Add support for AF_XDP zero-copy

[Sriram Yagnaraman <sriram.yagnaraman@est.tech>]

The first couple of patches adds helper funcctions to prepare for AF_XDP
zero-copy support which comes in the last couple of patches, one each
for Rx and TX paths.

As mentioned in v1 patchset [0], I don't have access to an actual IGB
device to provide correct performance numbers. I have used Intel 82576EB
emulator in QEMU [1] to test the changes to IGB driver.

The tests use one isolated vCPU for RX/TX and one isolated vCPU for the
xdp-sock application [2]. Hope these measurements provide at the least
some indication on the increase in performance when using ZC, especially
in the TX path. It would be awesome if someone with a real IGB NIC can
test the patch.
 
AF_XDP performance using 64 byte packets in Kpps.
Benchmark:	XDP-SKB		XDP-DRV		XDP-DRV(ZC)
rxdrop		220		235		350
txpush		1.000		1.000		410
l2fwd 		1.000		1.000		200

AF_XDP performance using 1500 byte packets in Kpps.
Benchmark:	XDP-SKB		XDP-DRV		XDP-DRV(ZC)
rxdrop		200		210		310
txpush		1.000		1.000		410
l2fwd 		0.900		1.000		160

[0]: https://lore.kernel.org/intel-wired-lan/20230704095915.9750-1-sriram.yagnaraman@est.tech/
[1]: https://www.qemu.org/docs/master/system/devices/igb.html
[2]: https://github.com/xdp-project/bpf-examples/tree/master/AF_XDP-example

v3->v4:
- NULL check buffer_info in igb_dump before dereferencing (Simon Horman)

v2->v3:
- Avoid TX unit hang when using AF_XDP zero-copy by setting time_stamp
  on the tx_buffer_info
- Fix uninitialized nb_buffs (Simon Horman)

v1->v2:
- Use batch XSK APIs (Maciej Fijalkowski)
- Follow reverse xmas tree convention and remove the ternary operator
  use (Simon Horman)


Sriram Yagnaraman (4):
  igb: prepare for AF_XDP zero-copy support
  igb: Introduce XSK data structures and helpers
  igb: add AF_XDP zero-copy Rx support
  igb: add AF_XDP zero-copy Tx support

 drivers/net/ethernet/intel/igb/Makefile   |   2 +-
 drivers/net/ethernet/intel/igb/igb.h      |  35 +-
 drivers/net/ethernet/intel/igb/igb_main.c | 186 ++++++--
 drivers/net/ethernet/intel/igb/igb_xsk.c  | 522 ++++++++++++++++++++++
 4 files changed, 698 insertions(+), 47 deletions(-)
 create mode 100644 drivers/net/ethernet/intel/igb/igb_xsk.c

-- 
2.34.1