netdev - Re: [PATCH RFC v3 0/5] Support fraglist GRO/GSO

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Message-ID: <CA+FuTSdVFguDHXYPJBRrLhzPWBaykd+7PRqEmGf_eOFC3iHpAg@mail.gmail.com>
Date:   Wed, 18 Sep 2019 12:17:08 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Steffen Klassert <steffen.klassert@...unet.com>
Cc:     Network Development <netdev@...r.kernel.org>,
        Paolo Abeni <pabeni@...hat.com>, marcelo.leitner@...il.com
Subject: Re: [PATCH RFC v3 0/5] Support fraglist GRO/GSO

On Wed, Sep 18, 2019 at 3:25 AM Steffen Klassert
<steffen.klassert@...unet.com> wrote:
>
> This patchset adds support to do GRO/GSO by chaining packets
> of the same flow at the SKB frag_list pointer. This avoids
> the overhead to merge payloads into one big packet, and
> on the other end, if GSO is needed it avoids the overhead
> of splitting the big packet back to the native form.
>
> Patch 1 Enables UDP GRO by default.
>
> Patch 2 adds a netdev feature flag to enable listifyed GRO,
> this implements one of the configuration options discussed
> at netconf 2019.
>
> Patch 3 adds a netdev software feature set that defaults to off
> and assigns the new listifyed GRO feature flag to it.
>
> Patch 4 adds the core infrastructure to do fraglist GRO/GSO.
>
> Patch 5 enables UDP to use fraglist GRO/GSO if configured and no
> GRO supported socket is found.

Very nice feature, Steffen. Aside from questions around performance,
my only question is really how this relates to GSO_BY_FRAGS.

More specifically, whether we can remove that in favor of using your
new skb_segment_list. That would actually be a big first step in
simplifying skb_segment back to something manageable.