netdev - Re: [PATCH intel-next v5 0/8] i40e: support XDP multi-buffer

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Date:   Fri, 17 Feb 2023 09:02:21 -0800
From:   Tony Nguyen <anthony.l.nguyen@...el.com>
To:     Tirthendu Sarkar <tirthendu.sarkar@...el.com>,
        <intel-wired-lan@...ts.osuosl.org>
CC:     <jesse.brandeburg@...el.com>, <netdev@...r.kernel.org>,
        <bpf@...r.kernel.org>, <magnus.karlsson@...el.com>,
        <maciej.fijalkowski@...el.com>
Subject: Re: [PATCH intel-next v5 0/8] i40e: support XDP multi-buffer



On 2/16/2023 6:00 AM, 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.
> 
> 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.

Hi Tirthendu,

Did you move over to next-queue/dev-queue because this series still 
isn't applying.

Also, I'm not seeing the truesize change on patch 4 as there are still 
issues being reported on it.

Thanks,
Tony

>      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(-)
>