netdev - Re: [PATCH net-next 08/33] xdp: cpumap redirect use frame_sz and increase skb

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Message-ID: <875zdp3rq4.fsf@toke.dk>
Date:   Fri, 24 Apr 2020 16:04:19 +0200
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Jesper Dangaard Brouer <brouer@...hat.com>, sameehj@...zon.com
Cc:     Jesper Dangaard Brouer <brouer@...hat.com>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, zorik@...zon.com, akiyano@...zon.com,
        gtzalik@...zon.com, Daniel Borkmann <borkmann@...earbox.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        John Fastabend <john.fastabend@...il.com>,
        Alexander Duyck <alexander.duyck@...il.com>,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        David Ahern <dsahern@...il.com>,
        Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        Ilias Apalodimas <ilias.apalodimas@...aro.org>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Saeed Mahameed <saeedm@...lanox.com>,
        steffen.klassert@...unet.com
Subject: Re: [PATCH net-next 08/33] xdp: cpumap redirect use frame_sz and increase skb_tailroom

Jesper Dangaard Brouer <brouer@...hat.com> writes:

> Knowing the memory size backing the packet/xdp_frame data area, and
> knowing it already have reserved room for skb_shared_info, simplifies
> using build_skb significantly.
>
> With this change we no-longer lie about the SKB truesize, but more
> importantly a significant larger skb_tailroom is now provided, e.g. when
> drivers uses a full PAGE_SIZE. This extra tailroom (in linear area) can be
> used by the network stack when coalescing SKBs (e.g. in skb_try_coalesce,
> see TCP cases where tcp_queue_rcv() can 'eat' skb).
>
> Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>

Acked-by: Toke Høiland-Jørgensen <toke@...hat.com>