netdev - Re: [net-next 08/15] net/mlx5e: CT: Preparation for offloading +trk+new ct rules

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Message-ID: <20210111235116.GA2595@horizon.localdomain>
Date:   Mon, 11 Jan 2021 20:51:16 -0300
From:   Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
To:     Roi Dayan <roid@...dia.com>
Cc:     Saeed Mahameed <saeed@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        Paul Blakey <paulb@...dia.com>,
        Saeed Mahameed <saeedm@...dia.com>, Oz Shlomo <ozsh@...dia.com>
Subject: Re: [net-next 08/15] net/mlx5e: CT: Preparation for offloading
 +trk+new ct rules

On Sun, Jan 10, 2021 at 09:52:55AM +0200, Roi Dayan wrote:
> 
> 
> On 2021-01-10 9:45 AM, Roi Dayan wrote:
> > 
> > 
> > On 2021-01-08 11:48 PM, Marcelo Ricardo Leitner wrote:
> > > Hi,
> > > 
> > > On Thu, Jan 07, 2021 at 09:30:47PM -0800, Saeed Mahameed wrote:
> > > > From: Roi Dayan <roid@...dia.com>
> > > > 
> > > > Connection tracking associates the connection state per packet. The
> > > > first packet of a connection is assigned with the +trk+new state. The
> > > > connection enters the established state once a packet is seen on the
> > > > other direction.
> > > > 
> > > > Currently we offload only the established flows. However, UDP traffic
> > > > using source port entropy (e.g. vxlan, RoCE) will never enter the
> > > > established state. Such protocols do not require stateful processing,
> > > > and therefore could be offloaded.
> > > 
> > > If it doesn't require stateful processing, please enlight me on why
> > > conntrack is being used in the first place. What's the use case here?
> > > 
> > 
> > The use case for example is when we have vxlan traffic but we do
> > conntrack on the inner packet (rules on the physical port) so
> > we never get established but on miss we can still offload as normal
> > vxlan traffic.
> > 
> 
> my mistake about "inner packet". we do CT on the underlay network, i.e.
> the outer header.

I miss why the CT match is being used there then. Isn't it a config
issue/waste of resources? What is CT adding to the matches/actions
being done on these flows?

> 
> > > > 
> > > > The change in the model is that a miss on the CT table will be forwarded
> > > > to a new +trk+new ct table and a miss there will be forwarded to
> > > > the slow
> > > > path table.
> > > 
> > > AFAICU this new +trk+new ct table is a wildcard match on sport with
> > > specific dports. Also AFAICU, such entries will not be visible to the
> > > userspace then. Is this right?
> > > 
> > >    Marcelo
> > > 
> > 
> > right.

Thanks,
Marcelo