netdev - Re: [PATCH v9 bpf-next 01/14] net: skbuff: add data_len field to skb_shared

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Message-ID: <e0b50540-0055-1f5c-af5f-0cd26616693a@redhat.com>
Date:   Tue, 29 Jun 2021 21:11:28 +0200
From:   Jesper Dangaard Brouer <jbrouer@...hat.com>
To:     Jakub Kicinski <kuba@...nel.org>,
        Alexander Duyck <alexander.duyck@...il.com>
Cc:     Lorenzo Bianconi <lorenzo.bianconi@...hat.com>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        bpf <bpf@...r.kernel.org>, Netdev <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>, shayagr@...zon.com,
        "Jubran, Samih" <sameehj@...zon.com>,
        John Fastabend <john.fastabend@...il.com>,
        David Ahern <dsahern@...nel.org>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Eelco Chaudron <echaudro@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Saeed Mahameed <saeed@...nel.org>,
        Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
        "Karlsson, Magnus" <magnus.karlsson@...el.com>,
        Tirthendu <tirthendu.sarkar@...el.com>
Subject: Re: [PATCH v9 bpf-next 01/14] net: skbuff: add data_len field to
 skb_shared_info


On 29/06/2021 20.37, Jakub Kicinski wrote:
> On Tue, 29 Jun 2021 11:18:38 -0700 Alexander Duyck wrote:
>> On Tue, Jun 29, 2021 at 10:08 AM Jakub Kicinski <kuba@...nel.org> wrote:
>>>> ack, I agree. I will fix it in v10.
>>> Why is XDP mb incompatible with LRO? I thought that was one of the use
>>> cases (mentioned by Willem IIRC).
>> XDP is meant to be a per packet operation with support for TX and
>> REDIRECT, and LRO isn't routable. So we could put together a large LRO
>> frame but we wouldn't be able to break it apart again. If we allow
>> that then we are going to need a ton more exception handling added to
>> the XDP paths.
>>
>> As far as GSO it would require setting many more fields in order to
>> actually make it offloadable by any hardware.
> It would require more work, but TSO seems to be explicitly stated
> as what the series builds towards (in the cover letter). It's fine
> to make choices we'd need to redo later, I guess, I'm just trying
> to understand the why.

This is also my understanding that LRO and TSO is what this patchset is 
working towards.

Sorry, I don't agree or understand this requested change.