Re: Load-balancing position field in DPDK load_balancer sample app vs. Hash table

[Yerden Zhumabekov <e_zhumabekov-8EHiFRVJVgQ@public.gmane.org>]

Hello Matt,

You can specify RSS configuration through rte_eth_dev_configure()
function supplied with this structure:

struct rte_eth_conf port_conf = {
    .rxmode = {
        .mq_mode    = ETH_MQ_RX_RSS,
         ...
    },
    .rx_adv_conf = {
        .rss_conf = {
            .rss_key = NULL,
            .rss_hf = ETH_RSS_IPV4 | ETH_RSS_IPV6,
        },
    },
    .....
};

In this case, RSS-hash is calculated over IP addresses only and with
default RSS key. Look at lib/librte_ether/rte_ethdev.h for other
definitions.


15.11.2014 0:49, Matt Laswell пишет:
> Hey Folks,
>
> This thread has been tremendously helpful, as I'm looking at adding
> RSS-based load balancing to my application in the not too distant
> future.  Many thanks to all who have contributed, especially regarding
> symmetric RSS.
>
> Not to derail the conversation too badly, but could one of you point
> me to some example code that demonstrates the steps needed to
> configure RSS?  We're using Niantic NICs, so I assume that this is
> pretty standard stuff, but having an example to study is a real leg up.
>
> Again, thanks for all of the information.
>
> --
> Matt Laswell
> laswell-bIuJOMs36aleGPcbtGPokg@public.gmane.org <mailto:laswell-bIuJOMs36aleGPcbtGPokg@public.gmane.org>
> infinite io, inc.
>
> On Fri, Nov 14, 2014 at 10:57 AM, Chilikin, Andrey
> <andrey.chilikin-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org <mailto:andrey.chilikin-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>> wrote:
>
>     Fortville supports symmetrical hashing on HW level, a patch for
>     i40e PMD was submitted a couple of weeks ago. For Niantic you can
>     use symmetrical  rss key recommended by Konstantin.
>
>     Regards,
>     Andrey
>
>     -----Original Message-----
>     From: dev [mailto:dev-bounces-VfR2kkLFssw@public.gmane.org
>     <mailto:dev-bounces-VfR2kkLFssw@public.gmane.org>] On Behalf Of Ananyev, Konstantin
>     Sent: Friday, November 14, 2014 4:50 PM
>     To: Yerden Zhumabekov; Kamraan Nasim; dev-VfR2kkLFssw@public.gmane.org
>     <mailto:dev-VfR2kkLFssw@public.gmane.org>
>     Cc: Yuanzhang Hu
>     Subject: Re: [dpdk-dev] Load-balancing position field in DPDK
>     load_balancer sample app vs. Hash table
>
>     > -----Original Message-----
>     > From: Yerden Zhumabekov [mailto:e_zhumabekov-8EHiFRVJVgQ@public.gmane.org
>     <mailto:e_zhumabekov-8EHiFRVJVgQ@public.gmane.org>]
>     > Sent: Friday, November 14, 2014 4:23 PM
>     > To: Ananyev, Konstantin; Kamraan Nasim; dev-VfR2kkLFssw@public.gmane.org
>     <mailto:dev-VfR2kkLFssw@public.gmane.org>
>     > Cc: Yuanzhang Hu
>     > Subject: Re: [dpdk-dev] Load-balancing position field in DPDK
>     > load_balancer sample app vs. Hash table
>     >
>     > I'd like to interject a question here.
>     >
>     > In case of flow classification, one might possibly prefer for
>     packets
>     > from the same flow to fall on the same logical core. With this '%'
>     > load balancing, it would require to get the same RSS hash value for
>     > packets with direct (src to dst) and swapped (dst to src) IPs and
>     > ports. Am I correct that hardware RSS calculation cannot provide
>     this symmetry?
>
>     As I remember, it is possible but you have to tweak rss key values.
>     Here is a paper describing how to do that:
>     http://www.ndsl.kaist.edu/~shinae/papers/TR-symRSS.pdf
>     <http://www.ndsl.kaist.edu/%7Eshinae/papers/TR-symRSS.pdf>
>
>     Konstantin
>
>     >
>     > 14.11.2014 20:44, Ananyev, Konstantin пишет:
>     > > If you have a NIC that is capable to do HW hash computation, then
>     > > you can do your load balancing based on that value.
>     > > Let say ixgbe/igb/i40e NICs can calculate RSS hash value based on
>     > > different combinations of dst/src Ips, dst/src ports.
>     > > This value can be stored inside mbuf for each RX packet by PMD
>     RX function.
>     > > Then you can do:
>     > > worker_id = mbuf->hash.rss % n_workersl
>     > >
>     > > That might to provide better balancing then using just one byte
>     > > value, plus should be a bit faster, as in that case your
>     balancer code don't need to touch packet's data.
>     > >
>     > > Konstantin
>     >
>     > --
>     > Sincerely,
>     >
>     > Yerden Zhumabekov
>     > State Technical Service
>     > Astana, KZ
>     >
>
>

-- 
Sincerely,

Yerden Zhumabekov
State Technical Service
Astana, KZ