On Thu, Feb 16, 2023 at 07:30:35PM +0530, Tirthendu Sarkar wrote:
> This patchset adds multi-buffer support for XDP. Tx side already has
> support for multi-buffer. This patchset focuses on Rx side. The last
> patch contains actual multi-buffer changes while the previous ones are
> preparatory patches.
>
> On receiving the first buffer of a packet, xdp_buff is built and its
> subsequent buffers are added to it as frags. While 'next_to_clean' keeps
> pointing to the first descriptor, the newly introduced 'next_to_process'
> keeps track of every descriptor for the packet.
>
> On receiving EOP buffer the XDP program is called and appropriate action
> is taken (building skb for XDP_PASS, reusing page for XDP_DROP, adjusting
> page offsets for XDP_{REDIRECT,TX}).
>
> The patchset also streamlines page offset adjustments for buffer reuse
> to make it easier to post process the rx_buffers after running XDP prog.
>
> With this patchset there does not seem to be any performance degradation
> for XDP_PASS and some improvement (~1% for XDP_TX, ~5% for XDP_DROP) when
> measured using xdp_rxq_info program from samples/bpf/ for 64B packets.
For series:
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@xxxxxxxxx>
>
> Changelog:
> v4 -> v5:
> - Change s/size/truesize [Tony]
> - Rebased on top of commit 9dd6e53ef63d ("i40e: check vsi type before
> setting xdp_features flag") [Lorenzo]
> - Changed size of on stack variable to u32 from u16.
>
> v3 -> v4:
> - Added non-linear XDP buffer support to xdp_features. [Maciej]
> - Removed double space. [Maciej]
>
> v2 -> v3:
> - Fixed buffer cleanup for single buffer packets on skb alloc
> failure.
> - Better naming of cleanup function.
> - Stop incrementing nr_frags for overflowing packets.
>
> v1 -> v2:
> - Instead of building xdp_buff on eop now it is built incrementally.
> - xdp_buff is now added to i40e_ring struct for preserving across
> napi calls. [Alexander Duyck]
> - Post XDP program rx_buffer processing has been simplified.
> - Rx buffer allocation pull out is reverted to avoid performance
> issues for smaller ring sizes and now done when at least half of
> the ring has been cleaned. With v1 there was ~75% drop for
> XDP_PASS with the smallest ring size of 64 which is mitigated by
> v2 [Alexander Duyck]
> - Instead of retrying skb allocation on previous failure now the
> packet is dropped. [Maciej]
> - Simplified page offset adjustments by using xdp->frame_sz instead
> of recalculating truesize. [Maciej]
> - Change i40e_trace() to use xdp instead of skb [Maciej]
> - Reserve tailroom for legacy-rx [Maciej]
> - Centralize max frame size calculation
>
> Tirthendu Sarkar (8):
> i40e: consolidate maximum frame size calculation for vsi
> i40e: change Rx buffer size for legacy-rx to support XDP multi-buffer
> i40e: add pre-xdp page_count in rx_buffer
> i40e: Change size to truesize when using i40e_rx_buffer_flip()
> i40e: use frame_sz instead of recalculating truesize for building skb
> i40e: introduce next_to_process to i40e_ring
> i40e: add xdp_buff to i40e_ring struct
> i40e: add support for XDP multi-buffer Rx
>
> drivers/net/ethernet/intel/i40e/i40e_main.c | 78 ++--
> drivers/net/ethernet/intel/i40e/i40e_trace.h | 20 +-
> drivers/net/ethernet/intel/i40e/i40e_txrx.c | 420 +++++++++++--------
> drivers/net/ethernet/intel/i40e/i40e_txrx.h | 21 +-
> 4 files changed, 307 insertions(+), 232 deletions(-)
>
> --
> 2.34.1
>
