linux-kernel - Re: [PATCH v3 net-next] netdev attribute to control xdpgeneric skb linearization

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Message-ID: <CAMOZA0JxgQ5Dvg7vvUk7TY8mx6Pd0raPXNBfbWup1JE1tr09fw@mail.gmail.com>
Date:   Fri, 28 Feb 2020 02:56:01 -0800
From:   Luigi Rizzo <lrizzo@...gle.com>
To:     Toke Høiland-Jørgensen <toke@...hat.com>
Cc:     netdev@...r.kernel.org, David Miller <davem@...emloft.net>,
        Jesper Dangaard Brouer <hawk@...nel.org>, sameehj@...zon.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 net-next] netdev attribute to control xdpgeneric skb linearization

On Fri, Feb 28, 2020 at 2:16 AM Toke Høiland-Jørgensen <toke@...hat.com> wrote:
>
> Luigi Rizzo <lrizzo@...gle.com> writes:
>
> > Add a netdevice flag to control skb linearization in generic xdp mode.
> >
> > The attribute can be modified through
> >       /sys/class/net/<DEVICE>/xdp_linearize
> > The default is 1 (on)
>
> Calling it just 'xdp_linearize' implies (to me) that it also affects
> driver-mode XDP. So maybe generic_xdp_linearize ?

done in v4, xdpgeneric_linearize for consistency

...

> > +Description:
> > +             boolean controlling whether skb should be linearized in
> > +             generic xdp. Defaults to true.
>
> Could you also add a few words explaining what the tradeoff here is?
> Something like: "turning this off can increase the performance of
> generic XDP at the cost of making the content of making the XDP program
> unable to access packet fragments after the first one"

done too in v4

thanks
luigi