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From:   Eric Dumazet <edumazet@google.com>
Date:   Mon, 13 Mar 2023 10:01:01 -0700
Message-ID: <CANn89iJfnK1q51ushoN-H4h8DCZBrbvwLB8JCyS6z3ViQczVVw@mail.gmail.com>
Subject: Re: [PATCH v3 1/2] gro: decrease size of CB
To:     Richard Gobert <richardbgobert@gmail.com>
Cc:     davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com,
        dsahern@kernel.org, alexanderduyck@fb.com, lucien.xin@gmail.com,
        lixiaoyan@google.com, iwienand@redhat.com, leon@kernel.org,
        ye.xingchen@zte.com.cn, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Mon, Mar 13, 2023 at 9:30=E2=80=AFAM Richard Gobert <richardbgobert@gmai=
l.com> wrote:
>
> The GRO control block (NAPI_GRO_CB) is currently at its maximum size.  Th=
is
> commit reduces its size by putting two groups of fields that are used onl=
y
> at different times into a union.
>
> Specifically, the fields frag0 and frag0_len are the fields that make up
> the frag0 optimisation mechanism, which is used during the initial parsin=
g
> of the SKB.

Note that these fields could also be stored in some auto variable,
instead of skb.

>
> The fields last and age are used after the initial parsing, while the SKB
> is stored in the GRO list, waiting for other packets to arrive.
>
> There was one location in dev_gro_receive that modified the frag0 fields
> after setting last and age. I changed this accordingly without altering t=
he
> code behaviour.
>
> Signed-off-by: Richard Gobert <richardbgobert@gmail.com>
> ---

SGTM, thanks.

Reviewed-by: Eric Dumazet <edumazet@google.com>