CODEWITHSUNDEEP
nicdpdk
Kamiar
Kamiar

Reputation: 174

How to set up RSS hash fuction in XL710 to receive IPv4 flow type?

In DPKD the ETH_RSS_IPV4 data flow is not activated by default for XL710 Intel NIC. So, when you want to distribute packets among lcores you have to select other IPv4 data flows which are supported by XL710, namely ETH_RSS_FRAG_IPV4, ETH_RSS_NONFRAG_IPV4_TCP, ETH_RSS_NONFRAG_IPV4_UDP, ETH_RSS_NONFRAG_IPV4_SCTP, and ETH_RSS_NONFRAG_IPV4_OTHER. However you will face a silly problem when you are dealing with the fragmented IP packets. If you choose to go with ETH_RSS_FRAG_IPV4 and ETH_RSS_NONFRAG_IPV4_TCP options then some fragmented packets of a connection will fall into another queue, because they don't have L4 port numbers. If you exclude ETH_RSS_NONFRAG_IPV4_TCP function then the ETH_RSS_FRAG_IPV4 hash function will not be applied to non-fragmented packets and those packets will go to queue 0. All other combination of hash functions will not work. So, what should we do?

Upvotes: 4

Views: 5635

Answers (1)

Kamiar
Kamiar

Reputation: 174

The behavior of XL710 is not compatible with the conventions in DPDK. So, you must directly work with the API offered by i40e driver in order to set up RSS for ETH_RSS_IPV4. As mentioned in the Intel® Ethernet Controller 710 Series Specification Update, page 18 (release Jan 2017):

Functions that require the Hash (RSS) filters on IPv4 packets should set all IPv4 PCTYPEs in the PFQF_HENA / VFQF_HENA (PCTYPEs 31, 33…36)

Supported packet types (PCTYPE) are mentioned in Intel® Ethernet Controller 710 Series Datasheet pages 597 and 598 (release Jan 2017). You can see that there is no packet type defined for IPv4.

However there is a solution. The clue is to modify the input set for all required flow types (or packet types). Let's try it with testpmd tool which is provided by DPDK in app folder. After compiling DPDK and the app, run the testpmd application:

./app/test-pmd/testpmd -c ff -n 2 -w 0a:00.0 -w 0a:00.1 -- -i --rxq=4 --txq=4

We have two XL710 in our system. With the following commands you can configure XL710 to behave as you want to support IPv4 data flow.

port config all rss all
set_hash_input_set 0 ipv4-tcp src-ipv4 select
set_hash_input_set 0 ipv4-tcp dst-ipv4 add
set_hash_input_set 0 ipv4-udp src-ipv4 select
set_hash_input_set 0 ipv4-udp dst-ipv4 add
set_hash_input_set 1 ipv4-tcp src-ipv4 select
set_hash_input_set 1 ipv4-tcp dst-ipv4 add
set_hash_input_set 1 ipv4-udp src-ipv4 select
set_hash_input_set 1 ipv4-udp dst-ipv4 add
set_hash_global_config 0 default ipv4-frag enable
set_hash_global_config 0 default ipv4-tcp enable
set_hash_global_config 0 default ipv4-udp enable
set_hash_global_config 1 default ipv4-frag enable
set_hash_global_config 1 default ipv4-tcp enable
set_hash_global_config 1 default ipv4-udp enable

It selects the proper input set for TCP and UDP flow types by removing the L4 port section. The set_hash_global_config command enables the symmetric hash if you need it. By modifying the TCP input set, it behaves just like Frag IPv4 flow type and as a result all packets belonging to the same connection go to the same lcore.

Note that the default input set for Frag IPv4 and NonFIPv4, Other is IP4-S and IP4-D. So it doesn't need to be modified. Remember to modify all other IPv4 flows input set and symmetric quality of them.

You can find the API functions of those commands by looking at the source code of the testpmd application.

Upvotes: 5

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