Date: Wed, 15 Jun 2016 19:04:53 -0500 From: Jim Thompson <jim@netgate.com> To: Navdeep Parhar <np@FreeBSD.org> Cc: Andrey Yakovlev <andy.yakov@ya.ru>, Dominik Schoeffmann <schoeffm@in.tum.de>, "net@freebsd.org" <net@freebsd.org> Subject: Re: Netmap Checksum Offloading Message-ID: <DA81EB82-4D4A-44F6-87F7-CD854AFF8694@netgate.com> In-Reply-To: <dd9058ce-ac8a-0c79-a8b0-e4814a17e504@FreeBSD.org> References: <57601DFA.2040008@in.tum.de> <470941466032510@web23o.yandex.ru> <dd9058ce-ac8a-0c79-a8b0-e4814a17e504@FreeBSD.org>
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Luiz Otavio O Souza (loos@) developed these for igb(4) and, by = extension, em(4) for use in netmap-fwd. He=E2=80=99s just gone back to Brazil with 82599 ixgb(4) hardware. = I=E2=80=99m sure he=E2=80=99ll develop similar patches for ixgb(4) in = the near future. Chelsio is also =E2=80=9Con the list=E2=80=9D, but I figured I=E2=80=99d = speak to np@ about it first. ;-) =20 We might do ixl(4) as well. =20 Before Luiz retired to Brazil, we discussed upstreaming these to = FreeBSD. We=E2=80=99re committed to make it happen, but I doubt they = make 11. Jim > On Jun 15, 2016, at 6:50 PM, Navdeep Parhar <np@FreeBSD.org> wrote: >=20 > 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 >=20 > 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. >=20 > Regards, > Navdeep >=20 >>=20 >> --=20 >> ./andy >>=20 >>=20 >> 14.06.2016, 12:15, "Dominik Schoeffmann" <schoeffm@in.tum.de>: >>> Dear Netmap Developers, >>>=20 >>> 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. >>>=20 >>> 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. >>>=20 >>> Best Regards, >>> Dominik Schoeffmann >>>=20 >>> [1] https://github.com/dschoeffm/MoonGen/tree/netmap >>> [2] https://github.com/dschoeffm/netmap/tree/mg-chksum-offloading >> _______________________________________________ >> freebsd-net@freebsd.org mailing list >> https://lists.freebsd.org/mailman/listinfo/freebsd-net >> To unsubscribe, send any mail to = "freebsd-net-unsubscribe@freebsd.org" >>=20 >=20 > _______________________________________________ > freebsd-net@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
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