[Intel-wired-lan] [PATCH v7 intel-next 6/9] ice: propagate xdp_ring onto rx_ring

[Kuruvinakunnel, George]

> From: Intel-wired-lan <intel-wired-lan-bounces at osuosl.org> On Behalf Of Maciej
> Fijalkowski
> Sent: Thursday, August 19, 2021 5:30 PM
> To: intel-wired-lan at lists.osuosl.org
> Cc: joamaki at gmail.com; Lobakin, Alexandr <alexandr.lobakin at intel.com>;
> netdev at vger.kernel.org; toke at redhat.com; bjorn at kernel.org; kuba at kernel.org;
> bpf at vger.kernel.org; davem at davemloft.net; Karlsson, Magnus
> <magnus.karlsson at intel.com>
> Subject: [Intel-wired-lan] [PATCH v7 intel-next 6/9] ice: propagate xdp_ring onto
> rx_ring
> 
> With rings being split, it is now convenient to introduce a pointer to XDP ring within
> the Rx ring. For XDP_TX workloads this means that xdp_rings array access will be
> skipped, which was executed per each processed frame.
> 
> Also, read the XDP prog once per NAPI and if prog is present, set up the local
> xdp_ring pointer. Reading prog a single time was discussed in [1] with some
> concern raised by Toke around dispatcher handling and having the need for going
> through the RCU grace period in the ndo_bpf driver callback, but ice currently is
> torning down NAPI instances regardless of the prog presence on VSI.
> 
> Although the pointer to XDP ring introduced to Rx ring makes things a lot
> slimmer/simpler, I still feel that single prog read per NAPI lifetime is beneficial.
> 
> Further patch that will introduce the fallback path will also get a profit from that as
> xdp_ring pointer will be set during the XDP rings setup.
> 
> [1]: https://lore.kernel.org/bpf/87k0oseo6e.fsf@toke.dk/
> 
> Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski at intel.com>
> ---
>  drivers/net/ethernet/intel/ice/ice_main.c     |  3 +++
>  drivers/net/ethernet/intel/ice/ice_txrx.c     | 23 +++++++++--------
>  drivers/net/ethernet/intel/ice/ice_txrx.h     |  1 +
>  drivers/net/ethernet/intel/ice/ice_txrx_lib.c | 10 +++-----
> drivers/net/ethernet/intel/ice/ice_txrx_lib.h |  2 +-
>  drivers/net/ethernet/intel/ice/ice_xsk.c      | 25 +++++++++++--------
>  6 files changed, 35 insertions(+), 29 deletions(-)
> 

Tested-by: George Kuruvinakunnel <george.kuruvinakunnel at intel.com>