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

["Zhang, Helin" <helin.zhang@intel.com>]

Hi Andrey

Yes, Fortville supports hardware symmetric hashing offload. I am waiting for the
comments of its patch set submitted recently, and hopefully it can be accepted soon.
To use it, we need to enable the hash function of symmetric, but not the default
one of Toeplitz hash function. Then we need to set the swap configurations of it.
In detail, it is to set the offsets and length of the packet contents to be symmetric
hashed.

For more details, please refer to its datasheet (possible chapter of 7.1.10 Hash Functions)!

Regards,
Helin

> -----Original Message-----
> From: Chilikin, Andrey
> Sent: Saturday, November 15, 2014 12:57 AM
> To: Ananyev, Konstantin; Yerden Zhumabekov; Kamraan Nasim; dev@dpdk.org
> Cc: Yuanzhang Hu; Zhang, Helin
> Subject: RE: [dpdk-dev] Load-balancing position field in DPDK load_balancer
> sample app vs. Hash table
> 
> 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@dpdk.org] On Behalf Of Ananyev, Konstantin
> Sent: Friday, November 14, 2014 4:50 PM
> To: Yerden Zhumabekov; Kamraan Nasim; dev@dpdk.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@sts.kz]
> > Sent: Friday, November 14, 2014 4:23 PM
> > To: Ananyev, Konstantin; Kamraan Nasim; dev@dpdk.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
> 
> 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
> >