Netmap Checksum Offloading

[Michael Tuexen]

> On 16 Jun 2016, at 08:40, Dominik Schoeffmann <schoeffm at in.tum.de> wrote:
> 
> Is the checksum offloading patch for the igb(4) driver available online?
> (I could not find it)
> I would really like to take a look at it, espacially the context
> descriptor part of it.
I would also be interested in it... For looking at SCTP checksum offloading.

Best regards
Michael
> 
> Best regards,
> Dominik
> 
> On 16.06.2016 02:04, Jim Thompson wrote:
>> 
>> Luiz Otavio O Souza (loos@) developed these for igb(4) and, by extension, em(4) for use in netmap-fwd.
>> 
>> He’s just gone back to Brazil with 82599 ixgb(4) hardware.  I’m sure he’ll develop similar patches for ixgb(4) in the near future.
>> 
>> Chelsio is also “on the list”, but I figured I’d speak to np@ about it first.  ;-)  
>> We might do ixl(4) as well.  
>> 
>> Before Luiz retired to Brazil, we discussed upstreaming these to FreeBSD.  We’re committed to make it happen, but I doubt they make 11.
>> 
>> Jim
>> 
>>> On Jun 15, 2016, at 6:50 PM, Navdeep Parhar <np at FreeBSD.org> wrote:
>>> 
>>> On 06/15/2016 16:15, Andrey Yakovlev wrote:
>>>> ive heard on bsdcan this year that some patches exist to add hwcsum offloading to netmap, hope to see it chelsio at least
>>> 
>>> cxgbe/cxl is a bit sneaky and will let you override netmap (on tx only).
>>> The ncxl interfaces declare themselves capable of checksumming but all
>>> such capabilities are disabled by default.  Just enable txcsum on the
>>> interface and the hardware will do checksum insertion on tx.  No way to
>>> solve the rx part entirely within the driver -- netmap has to be willing
>>> to accept checksum related flags from the driver.
>>> 
>>> Regards,
>>> Navdeep
>>> 
>>>> 
>>>> -- 
>>>> ./andy
>>>> 
>>>> 
>>>> 14.06.2016, 12:15, "Dominik Schoeffmann" <schoeffm at in.tum.de>:
>>>>> Dear Netmap Developers,
>>>>> 
>>>>> during the course of my bachelor's thesis, I modified a packet generator
>>>>> called MoonGen [1] in order to utilize netmap.
>>>>> One key component was to flexibly offload checksums for different kinds
>>>>> of packets (IPv4, UDP, TCP).
>>>>> The ixgbe netmap patch was modified [2] in order to construct context
>>>>> descriptors and suitable data descriptors. This is implemented in less
>>>>> than 250 LoC (including pseudo-header calculations).
>>>>> The man page states, that checksum offloading is available via ethtool,
>>>>> although a solution inside the netmap API might be a cleaner way for
>>>>> applications to actually use these features.
>>>>> Attached is a graph showing the performance implication of using
>>>>> offloading in the current implementation.
>>>>> As can be seen, offloading has only a minor impact.
>>>>> When regarding this data (and comparing it to other frameworks), please
>>>>> keep in mind, that internally a lot of per-packet effort is needed due
>>>>> to the software architecture of the packet generator.
>>>>> 
>>>>> The question being:
>>>>> Would it not make sense to include checksum offloading inside of netmap
>>>>> in order to accomodate applications operating on layer 3 and above?
>>>>> As these programs need to calculate the checksums in software, it would
>>>>> be just as fast to move these calculations to the kernel for NICs
>>>>> without checksum offloading support (and the kernel would act as a library).
>>>>> The problem which currently is imposed by the fact, that netmap exports
>>>>> the complete ring, is that context descriptors disrupt the data
>>>>> descriptors, which is unpleasant for the application.
>>>>> But you may find the data interesting nevertheless.
>>>>> 
>>>>> Best Regards,
>>>>> Dominik Schoeffmann
>>>>> 
>>>>> [1] https://github.com/dschoeffm/MoonGen/tree/netmap
>>>>> [2] https://github.com/dschoeffm/netmap/tree/mg-chksum-offloading
>>>> _______________________________________________
>>>> freebsd-net at freebsd.org mailing list
>>>> https://lists.freebsd.org/mailman/listinfo/freebsd-net
>>>> To unsubscribe, send any mail to "freebsd-net-unsubscribe at freebsd.org"
>>>> 
>>> 
>>> _______________________________________________
>>> freebsd-net at freebsd.org mailing list
>>> https://lists.freebsd.org/mailman/listinfo/freebsd-net
>>> To unsubscribe, send any mail to "freebsd-net-unsubscribe at freebsd.org"
>> 
>