Rss hash on mellanox 100G card

Rss hash on mellanox 100G card

[Yaron Illouz]

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I am using Mellanox Technologies MT27800 Family [ConnectX-5], using dpdk 19 with multi rx queue with rss port_conf.rx_adv_conf.rss_conf.rss_hf=(ETH_RSS_IP | ETH_RSS_UDP | ETH_RSS_TCP)

I analyze traffic and need all packet of same session to arrive to the same process ( session for now can be ip+port)

So Packet that have the same ip + port arrive to the same queue.

But If some packet are ip fragmented, packet arrive to different process. It is a problem!

How can i calculate the hash value in the c++ code, like it is done in the card, so i can reassemble packets and send them to the same process like the non fragmented packets?



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Re: Rss hash on mellanox 100G card

[Medvedkin, Vladimir]

Hi Yaron,

On 09/01/2022 13:20, Yaron Illouz wrote:
> I am using Mellanox Technologies MT27800 Family [ConnectX-5], using dpdk 
> 19 with multi rx queue with rss 
> port_conf.rx_adv_conf.rss_conf.rss_hf=(ETH_RSS_IP | ETH_RSS_UDP | 
> ETH_RSS_TCP)
> 
> I analyze traffic and need all packet of same session to arrive to the 
> same process ( session for now can be ip+port)
> 
> So Packet that have the same ip + port arrive to the same queue.
> 
> But If some packet are ip fragmented, packet arrive to different 
> process. It is a problem!
> 
> How can i calculate the hash value in the c++ code, like it is done in 
> the card, so i can reassemble packets and send them to the same process 
> like the non fragmented packets?
> 

I think you need rte_softrss/rte_thash_gfni() , details could be found here:
https://doc.dpdk.org/guides/prog_guide/toeplitz_hash_lib.html

Or as an alternative option you can configure your NIC hash function to 
calculate the hash on L3 fields only.

-- 
Regards,
Vladimir