[dpdk-users] Mellanox rss hash information

Saleh, Omran omran.saleh at sap.com
Wed Dec 28 09:28:34 CET 2016

Hi All,
Currently, I am using DPDK 16.11 with Mellanox NIC adapters (mlx5). I encounter a problem that the RSS hash value from mbuf  (mbug.hash->rss) is not the same as calculated from rte_softrss(). It is completely different.
I am using the default hash key from mlx5

uint8_t rss_hash_default_key[] = {
        0x2c, 0xc6, 0x81, 0xd1,
        0x5b, 0xdb, 0xf4, 0xf7,
        0xfc, 0xa2, 0x83, 0x19,
        0xdb, 0x1a, 0x3e, 0x94,
        0x6b, 0x9e, 0x38, 0xd9,
        0x2c, 0x9c, 0x03, 0xd1,
        0xad, 0x99, 0x44, 0xa7,
        0xd9, 0x56, 0x3d, 0x59,
        0x06, 0x3c, 0x25, 0xf3,
        0xfc, 0x1f, 0xdc, 0x2a,
And the following call:
auto hash = rte_softrss(&tuple.v4.src_addr, RTE_THASH_V4_L4_LEN, rss_hash_default_key);
with RSS configurations as the following:

port_conf.rxmode.mq_mode = ETH_MQ_RX_RSS;
port_conf.rx_adv_conf.rss_conf.rss_hf = ETH_RSS_NONFRAG_IPV4_TCP;
port_conf.rx_adv_conf.rss_conf.rss_key= rss_hash_default_key;
port_conf.rx_adv_conf.rss_conf.rss_key_len = 40;

This is working perfectly with ixgbe  but Mellanox not. Can you help me to figure out what is the problem? What is the default Toeplitz function for mlx5?!

My NIC adapters are  Mellanox Technologies MT27700 Family [ConnectX-4]
With firmware version 12.16.1006 and ofed version  3.3-2.0.0

uname -a : Linux ibmhanar16 3.12.49-11-default #1 SMP Wed Nov 11 20:52:43 UTC 2015 (8d714a0) x86_64 x86_64 x86_64 GNU/Linux

Thank you
Best regards,
Omran Saleh

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