[dpdk-dev] [PATCH v3 04/14] net/mlx5: support Rx tunnel type identification

[Xueming(Steven) Li]

> -----Original Message-----
> From: Nélio Laranjeiro <nelio.laranjeiro at 6wind.com>
> Sent: Tuesday, April 17, 2018 3:20 PM
> To: Xueming(Steven) Li <xuemingl at mellanox.com>
> Cc: Adrien Mazarguil <adrien.mazarguil at 6wind.com>; Shahaf Shuler <shahafs at mellanox.com>; dev at dpdk.org;
> Olivier Matz <olivier.matz at 6wind.com>
> Subject: Re: [PATCH v3 04/14] net/mlx5: support Rx tunnel type identification
> 
> On Tue, Apr 17, 2018 at 04:53:15AM +0000, Xueming(Steven) Li wrote:
> >
> >
> > > -----Original Message-----
> > > From: Adrien Mazarguil <adrien.mazarguil at 6wind.com>
> > > Sent: Tuesday, April 17, 2018 12:03 AM
> > > To: Xueming(Steven) Li <xuemingl at mellanox.com>
> > > Cc: Nélio Laranjeiro <nelio.laranjeiro at 6wind.com>; Shahaf Shuler
> > > <shahafs at mellanox.com>; dev at dpdk.org; Olivier Matz
> > > <olivier.matz at 6wind.com>
> > > Subject: Re: [PATCH v3 04/14] net/mlx5: support Rx tunnel type
> > > identification
> > >
> > > On Mon, Apr 16, 2018 at 03:27:37PM +0000, Xueming(Steven) Li wrote:
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: Adrien Mazarguil <adrien.mazarguil at 6wind.com>
> > > > > Sent: Monday, April 16, 2018 9:48 PM
> > > > > To: Xueming(Steven) Li <xuemingl at mellanox.com>
> > > > > Cc: Nélio Laranjeiro <nelio.laranjeiro at 6wind.com>; Shahaf Shuler
> > > > > <shahafs at mellanox.com>; dev at dpdk.org; Olivier Matz
> > > > > <olivier.matz at 6wind.com>
> > > > > Subject: Re: [PATCH v3 04/14] net/mlx5: support Rx tunnel type
> > > > > identification
> > > > >
> > > > > On Mon, Apr 16, 2018 at 01:32:49PM +0000, Xueming(Steven) Li wrote:
> > > > > >
> > > > > > > -----Original Message-----
> > > > > > > From: Adrien Mazarguil <adrien.mazarguil at 6wind.com>
> > > > > > > Sent: Monday, April 16, 2018 5:28 PM
> > > > > > > To: Xueming(Steven) Li <xuemingl at mellanox.com>
> > > > > > > Cc: Nélio Laranjeiro <nelio.laranjeiro at 6wind.com>; Shahaf
> > > > > > > Shuler <shahafs at mellanox.com>; dev at dpdk.org; Olivier Matz
> > > > > > > <olivier.matz at 6wind.com>
> > > > > > > Subject: Re: [PATCH v3 04/14] net/mlx5: support Rx tunnel
> > > > > > > type identification
> > > > > > >
> > > > > > > On Mon, Apr 16, 2018 at 08:05:13AM +0000, Xueming(Steven) Li wrote:
> > > > > > > >
> > > > > > > >
> > > > > > > > > -----Original Message-----
> > > > > > > > > From: Nélio Laranjeiro <nelio.laranjeiro at 6wind.com>
> > > > > > > > > Sent: Monday, April 16, 2018 3:29 PM
> > > > > > > > > To: Xueming(Steven) Li <xuemingl at mellanox.com>
> > > > > > > > > Cc: Shahaf Shuler <shahafs at mellanox.com>; dev at dpdk.org;
> > > > > > > > > Olivier Matz <olivier.matz at 6wind.com>; Adrien Mazarguil
> > > > > > > > > <adrien.mazarguil at 6wind.com>
> > > > > > > > > Subject: Re: [PATCH v3 04/14] net/mlx5: support Rx
> > > > > > > > > tunnel type identification
> > > > > > > > >
> > > > > > > > > On Sat, Apr 14, 2018 at 12:57:58PM +0000, Xueming(Steven) Li wrote:
> > > > > > > > > > +Adrien
> > > > > > > > > >
> > > > > > > > > > > -----Original Message-----
> > > > > > > > > > > From: Nélio Laranjeiro <nelio.laranjeiro at 6wind.com>
> > > > > > > > > > > Sent: Friday, April 13, 2018 9:03 PM
> > > > > > > > > > > To: Xueming(Steven) Li <xuemingl at mellanox.com>
> > > > > > > > > > > Cc: Shahaf Shuler <shahafs at mellanox.com>;
> > > > > > > > > > > dev at dpdk.org; Olivier Matz <olivier.matz at 6wind.com>
> > > > > > > > > > > Subject: Re: [PATCH v3 04/14] net/mlx5: support Rx
> > > > > > > > > > > tunnel type identification
> > > > > > > > > > >
> > > > > > > > > > > +Olivier,
> > > > > > > > > > >
> > > > > > > > > > > On Fri, Apr 13, 2018 at 07:20:13PM +0800, Xueming Li wrote:
> > > > > > > > > > > > This patch introduced tunnel type identification based on flow rules.
> > > > > > > > > > > > If flows of multiple tunnel types built on same
> > > > > > > > > > > > queue, RTE_PTYPE_TUNNEL_MASK will be returned,
> > > > > > > > > > > > user application could use bits in flow mark as tunnel type identifier.
> > > > > > > > > > >
> > > > > > > > > > > For an application it will mean the packet embed all
> > > > > > > > > > > tunnel types defined in DPDK, to make such thing you
> > > > > > > > > > > need a RTE_PTYPE_TUNNEL_UNKNOWN which does not exists currently.
> > > > > > > > > >
> > > > > > > > > > There was a RTE_PTYPE_TUNNEL_UNKNOWN definition, but
> > > > > > > > > > removed due to
> > > > > > > > > discussion.
> > > > > > > > > > So I think it good to add it in the patchset of reviewed by Adrien.
> > > > > > > > >
> > > > > > > > > Agreed,
> > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > > Even with it, the application still needs to parse
> > > > > > > > > > > the packet to discover which tunnel the packet
> > > > > > > > > > > embed, is there any benefit having such bit?  Not so sure.
> > > > > > > > > >
> > > > > > > > > > With a tunnel flag, checksum status represent inner checksum.
> > > > > > > > >
> > > > > > > > > Not sure this is generic enough, MLX5 behaves as this,
> > > > > > > > > but how behaves other NICs?  It should have specific
> > > > > > > > > bits for inner checksum if all NIC don't have the same behavior.
> > > > > > > >
> > > > > > > > From my understanding, if outer checksum invalid, the
> > > > > > > > packet can't be received as a tunneled packet, but a
> > > > > > > > normal packet, thus checksum flags always result of inner for a valid tunneled packet.
> > > > > > >
> > > > > > > Yes, since checksum validation information covers all layers
> > > > > > > at once (outermost to the innermost recognized), the presence of an "unknown tunnel"
> > > > > > > bit implicitly means outer headers are OK.
> > > > > > >
> > > > > > > Now regarding the addition of RTE_PTYPE_TUNNEL_UNKNOWN, the
> > > > > > > main issue I see is that it's implicit, as in getting 0
> > > > > > > after and'ing packet types with RTE_PTYPE_TUNNEL_MASK means either not present or unknown
> type.
> > > > > >
> > > > > > How about define RTE_PTYPE_TUNNEL_UNKNOWN same ask
> > > > > > RTE_PTYPE_TUNNEL_MASK? And'ding packet types always return a non-zero value.
> > > > >
> > > > > I mean the value already exists, it's implicitly 0. Adding one
> > > > > with the same value as RTE_PTYPE_TUNNEL_MASK could be seen as a
> > > > > waste of a value otherwise usable for an actual tunnel type (there are only 4 bits).
> > > > >
> > > > > > > How about not setting any tunnel bit and let applications
> > > > > > > rely on the presence of RTE_PTYPE_INNER_* to determine that
> > > > > > > there is a tunnel of unknown type? The rationale being that
> > > > > > > a tunneled packet without an inner payload is
> > > > > kind of pointless anyway.
> > > > > >
> > > > > > An unknown type doesn't break anything, neither enum bits, straightforward IMHO.
> > > > >
> > > > > Keep in mind that mbuf packet types report what is identified.
> > > > > All the definitions in this file name a specific protocol. For
> > > > > instance there is no such definition as "L3 present" or "L4
> > > > > present". "Tunnel present" doesn't make a lot
> > > of sense on its own either.
> > > > >
> > > > > Don't you agree that reporting at least one inner ptype while
> > > > > leaving tunnel ptype to 0 automatically addresses this issue?
> > > >
> > > > Currently, no inner L2 ptype, so for packet with only L2, it will be recognized as non-tunnel
> packet.
> > >
> > > Applications can live with it. Don't bother with a ptype API change
> > > at this point, it raises more issues than it solves.
> > >
> > > Given the size of the series, let's deal with that later through a
> > > separate task and according to user feedback.
> >
> > Nelio, so I'll leave it as it is, are you okay with it?
> 
> I agree with Adrien, if you are not able to say which kind of tunnel it is, don't set it in the mbuf.

It's useful to have a tunnel flag otherwise have to change the code to iterate tunnel_types which
would slow down the flow creation.
		rxq_ctrl->tunnel_types[tunnel] += 1;
		if (rxq_data->tunnel != flow->tunnel)
			rxq_data->tunnel = rxq_data->tunnel ?
					   RTE_PTYPE_TUNNEL_MASK :
					   flow->tunnel;

> 
> Regards,
> 
> --
> Nélio Laranjeiro
> 6WIND