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

Xueming(Steven) Li xuemingl at mellanox.com
Tue Apr 17 06:53:15 CEST 2018



> -----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?

> 
> --
> Adrien Mazarguil
> 6WIND


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