On Tue, Aug 8, 2017 at 2:29 PM, Liron Himi <lir...@marvell.com> wrote:
> See comments inline > > > > Liron > > > > *From:* Bill Fischofer [mailto:bill.fischo...@linaro.org] > *Sent:* Tuesday, August 08, 2017 22:07 > *To:* Liron Himi <lir...@marvell.com> > *Cc:* lng-odp@lists.linaro.org > *Subject:* [EXT] Re: [lng-odp] Parser configuration > > > > External Email > ------------------------------ > > > > > > On Tue, Aug 8, 2017 at 1:43 PM, Liron Himi <lir...@marvell.com> wrote: > > Hi, > > I have a query regarding the new parser configuration. > Let's say application set it to 'ODP_PKTIO_PARSER_LAYER_L2', does it means > that the platform implementation must parse and recognize all eth-type that > have ODP API such as ARP,VLAN, etc.? same for ICMP, etc for L3? > > > > ODP defines the protocols it supports at a given layer and implementations > that parse at that layer are expected to support those protocols. > Implementations are free to parse deeper than requested, but must parse to > at least the configured layer on a per-pktio basis. The parse results are > accessed by the various odp_packet_has_xxx() APIs, and these are exercised > by the pktio validation test suite. > > > > However, while VLAN is a Layer 2 protocol, ARP is a Layer 3 protocol and > ICMP is a Layer 4 protocol. > > > > > I'm asking it as I tried to run the parser validation tests and only the > ones with ARP and ICMP are failing. > It seems that the validation tests expect from the platform implementation > to flag it. > > > > The validation test sets ODP_PKTIO_PARSER_LAYER_ALL and then tests > individual packet types on a per-layer basis. Does your platform not parse > ARP or ICMP? > > *[L.H.] Our platform implementation only support the protocols that are > supported by our HW. We don’t do additional SW parsing as it will have > performance penalty.* > > > Does the HW signal whether it encountered protocols it didn't recognize? That would allow you to do supplemental SW parsing only in such cases, which would permit the current validation tests to pass without incurring extra overhead for the expected cases. > > Is that only validation test assumption or this is the real assumption and > expectation from the platform? > Maybe it is good to extend the parser with supported protocol per layer in > the capabilities. Same as we have for checksum support. > > > > That might be an interesting addition, but may not buy much. The parser > layer controls were added to allow applications to hint platforms that do > SW parsing since in such platforms parsing to a depth that isn't needed by > the application wastes cycles. Platforms that have HW parsers typically > parse everything at line rate anyway, so these controls are effectively > ignored. > > *[L.H.] Our HW currently do have HW parsing but not all protocols are > identify by it. E.g. In L4 we only identify UDP and TCP.* > > *So the above suggestion will allow us to communicate with the application > on the supported protocols. * > > *I think it is make sense that along with the supported parsing layer the > platform implementation will also specific the supported protocols.* > > *As probably some platform will need sw parsing to support all protocol, > maybe application will also want to give a hint on the required protocols.* > > *e.g. TCP application that only need TCP support and no other protocols.* > > *In the future ODP may extend its protocols support, I guess that forcing > the platform to support them even if require SW parsing is a good idea.* > The larger problem is that there are many protocols that ODP currently doesn't recognize and when you add to that application-specific shim layers, tunneling options, etc. it becomes clear that the current predefined protocol set is too restrictive and inflexible to meet application needs going forward. For this reason we'd like to explore integration with more advanced technologies like P4, which would permit the parser definitions to be offloaded from the ODP API specification and modularized. Applications would then be free to define their own arbitrary packet formats, or to select from a library of predefined packet templates that cover these extended parsing needs while still being able to take advantage of HW-accelerated parsing. > > > > Regards, > Liron > > >
