> On 2023/4/24 21:10, Maciej Fijalkowski wrote: > >>> There was a discussion in the past to reduce XDP_PACKET_HEADROOM to 192B but > >>> this is not merged yet and it is not related to this series. We can address > >>> your comments in a follow-up patch when XDP_PACKET_HEADROOM series is merged. > > > > Intel drivers still work just fine at 192 headroom and split the page but > > it makes it problematic for BIG TCP where MAX_SKB_FRAGS from shinfo needs > > I am not sure why we are not enabling skb_shinfo(skb)->frag_list to support > BIG TCP instead of increasing MAX_SKB_FRAGS, perhaps there was some disscution > about this in the past I am not aware of? > > > to be increased. So it's the tailroom that becomes the bottleneck, not the > > headroom. I believe at some point we will convert our drivers to page_pool > > with full 4k page dedicated for a single frame. > > Can we use header splitting to ensure there is enough tailroom for > napi_build_skb() or xdp_frame with shinfo? > since veth_convert_skb_to_xdp_buff() runs in veth_poll() I think we can use napi_build_skb(). I tested it and we get an improvement (9.65Gbps vs 9.2Gbps for 1500B frames). Regards, Lorenzo
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