linux-kernel - Re: [PATCH v2] tun: avoid high-order page allocation for packet header

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Message-ID: <CANn89iLV0iEeQy19wn+Vfmhpgr6srVpf3L+oBvuDyLRQXfoMug@mail.gmail.com>
Date:   Tue, 1 Aug 2023 11:37:27 +0200
From:   Eric Dumazet <edumazet@...gle.com>
To:     Tahsin Erdogan <trdgn@...zon.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] tun: avoid high-order page allocation for packet header

On Tue, Aug 1, 2023 at 1:07 AM Tahsin Erdogan <trdgn@...zon.com> wrote:
>
> When GSO is not enabled and a packet is transmitted via writev(), all
> payload is treated as header which requires a contiguous memory allocation.
> 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 change
> makes writev() and sendmsg() more consistent.
>
> Signed-off-by: Tahsin Erdogan <trdgn@...zon.com>
> ---

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

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

Thanks.