[PATCH iwl-next 0/3] iavf: defer loading netmem_desc

[Matt Vollrath <tactii@gmail.com>]

In a few places libeth and the iavf driver inspect which page pool is
attached to a netmem_ref. This forces an immediate load of the
netmem_desc struct for each buffer in the Rx loop.

Defer or eliminate these loads of netmem_desc from the driver fast path
by using the page_pool ref in the first cache line of iavf_ring instead.

There are only two paths out of the Rx loop where netmem_desc needs to
be consumed:
* The "very rare" case of libeth_rx_sync_for_cpu calling
  libeth_rx_recycle_slow and indicating that there was no data. This
  could be similarly factored out, but not by this series.
* GRO merging a frame into an existing aggregate stream. In this case,
  the cold load of netmem_desc may overlap the payload prefetch started
  by iavf_build_skb, which is now no longer dependent on netmem_desc to
  start.

Matt Vollrath (3):
  libeth: add __libeth_rx_sync_for_cpu
  iavf: use __libeth_rx_sync_for_cpu
  iavf: use cached page_pool ref in skb helpers

 drivers/net/ethernet/intel/iavf/iavf_txrx.c | 18 ++++++----
 include/net/libeth/rx.h                     | 37 +++++++++++++++------
 2 files changed, 37 insertions(+), 18 deletions(-)


base-commit: 5c458073553f0ef74f5c8db1bd459c87c722a299
-- 
2.43.0