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

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
infinite io, inc.

On Fri, Nov 14, 2014 at 10:57 AM, Chilikin, Andrey <
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] On Behalf Of Ananyev, Konstantin
Sent: Friday, November 14, 2014 4:50 PM
To: Yerden Zhumabekov; Kamraan Nasim; 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

quoted

-----Original Message-----
From: Yerden Zhumabekov [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
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

quoted

14.11.2014 20:44, Ananyev, Konstantin пишет:

quoted

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.

quoted

quoted

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.

quoted

quoted

Konstantin

--
Sincerely,

Yerden Zhumabekov
State Technical Service
Astana, KZ