[dpdk-dev] Symmetric RSS Hashing in DPDK

[Kamraan Nasim]

Hi DPDK community,

Any better RSS hash keys out there?

--Kam

On Wed, Dec 17, 2014 at 2:12 PM, Kamraan Nasim <knasim at sidebandnetworks.com>
wrote:
>
> Thank you Jeriel. 0x00 0x01 works and I can get bi-directional symmetry
> but you are right, it compromises the packet distribution. I am seeing
> vastly different 5 tuples hashed with the same value.
>
> Will let you know if I find a better alternative.
>
> --Kam
>
> On Tue, Dec 16, 2014 at 5:17 PM, Jeriel Smith <sjeriel2 at gmail.com> wrote:
>>
>> Hi Kamraan,
>>       Even i noticed it with "0x6d5a". Currently, I use a continuous
>> pattern of "0x00 0x01" which helps in getting a symmetrical hashing. But,
>> the packet spraying is not that good as "0x6d5a". Please let me know if you
>> find a alternative.
>> Thanks,
>> Jeriel
>>
>>
>>> ---------- Forwarded message ----------
>>> From: Kamraan Nasim <knasim at sidebandnetworks.com>
>>> Date: Tue, Dec 16, 2014 at 11:52 AM
>>> Subject: [dpdk-dev] Symmetric RSS Hashing in DPDK
>>> To: dev at dpdk.org
>>> Cc: Steve Noble <snoble at sidebandnetworks.com>, Jun Du <
>>> jdu at sidebandnetworks.com>, Ashish Juneja <ajuneja at sidebandnetworks.com>
>>>
>>> Hello,
>>>
>>> My DPDK application requires bidirectional TCP flows to have the same RSS
>>> hash however default RSS hashing is *asymmetric*.
>>>
>>>
>>> There are posts such as:
>>> http://dpdk.info/ml/archives/dev/2014-February/001460.html
>>>
>>> which point to a symmetric RSS key(0x6d5a). I have tried using it but it
>>> is
>>> still hashing bi-directional flows separately. I am using an 82599 NIC.
>>>
>>> Have others come across this? What other options are available(I presume
>>> S/W hashing)?
>>>
>>> Appreciate any help I can get on this :)
>>>
>>> #define RSS_HASH_KEY_LENGTH 40
>>> static uint8_t hash_key[RSS_HASH_KEY_LENGTH] = {
>>>         0x6D, 0x5A, 0x6D, 0x5A, 0x6D, 0x5A, 0x6D, 0x5A,
>>>         0x6D, 0x5A, 0x6D, 0x5A, 0x6D, 0x5A, 0x6D, 0x5A,
>>>         0x6D, 0x5A, 0x6D, 0x5A, 0x6D, 0x5A, 0x6D, 0x5A,
>>>         0x6D, 0x5A, 0x6D, 0x5A, 0x6D, 0x5A, 0x6D, 0x5A,
>>>         0x6D, 0x5A, 0x6D, 0x5A, 0x6D, 0x5A, 0x6D, 0x5A,
>>> };
>>> // ethernet rx config
>>> static struct rte_eth_conf port_conf = {
>>>     .rxmode = {
>>>         .mq_mode    = ETH_MQ_RX_RSS,
>>>         .split_hdr_size = 0,
>>>         .header_split   = 0, /**< Header Split disabled */
>>>         .hw_ip_checksum = 1, /**< IP checksum offload enabled */
>>>         .hw_vlan_filter = 0, /**< VLAN filtering disabled */
>>>         .jumbo_frame    = 0, /**< Jumbo Frame Support disabled */
>>>         .hw_strip_crc   = 0, /**< CRC stripped by hardware */
>>>     },
>>>     .rx_adv_conf = {
>>>         .rss_conf = {
>>>             .rss_key = hash_key,
>>>             .rss_hf  = ETH_RSS_PROTO_MASK,
>>>         },
>>>     },
>>>     .txmode = {
>>>                 .mq_mode = ETH_MQ_TX_NONE,
>>>     },
>>> };
>>>
>>>
>>> Thanks,
>>> Kam
>>>
>>