On 22 September 2014 15:35, Jim Thompson <j...@netgate.com> wrote: > >> On Sep 22, 2014, at 5:15 PM, Adrian Chadd <adr...@freebsd.org> wrote: >> >> On 22 September 2014 13:39, Elof Ofel <elof...@hotmail.com> wrote: >>> Hi Adrian! >>> >>> Now this sounds promising! All my sensors use the ixgbe driver. >>> However, my skills in programming/compiling isn't vast. I know how to patch >>> and use poudriere. That's about it. >>> >>> I must admit I don't really understand what you mean with "patch it to use a >>> symmetric RSS key", but it sounds like the functionality I'm looking for is >>> not yet there in the driver. >> >> A few years ago a couple of researchers figured out you could abuse >> the toeplitz hash to do symmetric RSS hashing: >> >> http://www.ndsl.kaist.edu/~shinae/papers/TR-symRSS.pdf >> >> This means that the same RSS hash value is chosen no matter which >> direction the traffic is going on. >> This is what you need to ensure that the packets going both directions >> in a connection end up in the same NIC hardware receive ring. >> >> So, all you have to do (!) is: >> >> * grab freebsd-head, because the ixgbe driver there has some recent >> bug fixes that you need for this to completely work; >> * look at ixgbe_initialise_rss_mapping() - that's where the RSS key, >> mapping and RSS hash types are configured; >> * patch it to use the example symmetric RSS key that was provided in the >> paper; > > possible that XOR-ing the values to be hashed will produce a similar result. > Of course, this is software, not hardware generation of Toeplitz. > >> * patch it to only hash on IPv4 / IPv6 2-tuple, that way you don't end >> up with IPv4/IPv6 fragments in the wrong queue; > > I hope these two aren’t embedded in the code. The coming Intel devices both > support the symmetric RSS key and > will correctly hash on ipv4/ipv4 4 tuple.
> See section 7.1.10.1 and 7.1.10.3 in > http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/xl710-10-40-controller-datasheet.pdf I think it'll still do the same thing - it'll not be able to 4-tuple IPv4 frames that are fragmented, as the non-first frame doesn't have the TCP/UDP information. (The support for symmetric RSS by XORing the source/destination bits is very nice - we'll have to teach freebsd's RSS code about that at some point.) -a _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
