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From:   Eric Dumazet <edumazet@google.com>
Date:   Tue, 1 Aug 2023 11:37:27 +0200
Message-ID: <CANn89iLV0iEeQy19wn+Vfmhpgr6srVpf3L+oBvuDyLRQXfoMug@mail.gmail.com>
Subject: Re: [PATCH v2] tun: avoid high-order page allocation for packet header
To:     Tahsin Erdogan <trdgn@amazon.com>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
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On Tue, Aug 1, 2023 at 1:07=E2=80=AFAM Tahsin Erdogan <trdgn@amazon.com> wr=
ote:
>
> When GSO is not enabled and a packet is transmitted via writev(), all
> payload is treated as header which requires a contiguous memory allocatio=
n.
> This allocation request is harder to satisfy, and may even fail if there =
is
> enough fragmentation.
>
> Note that sendmsg() code path limits the linear copy length, so this chan=
ge
> makes writev() and sendmsg() more consistent.
>
> Signed-off-by: Tahsin Erdogan <trdgn@amazon.com>
> ---

I will have to tweak one existing packetdrill test, nothing major.

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

Thanks.