Re: [dpdk-dev] Redirection Table

[Ivan Boule <ivan.boule@6wind.com>]

On 12/31/2013 08:45 PM, Michael Quicquaro wrote:
> Has anyone used the "port config all reta (hash,queue)" command of testpmd
> with any success?
>
> I haven't found much documentation on it.
>
> Can someone provide an example on why and how it was used.
>
> Regards and Happy New Year,
> Michael Quicquaro
Hi Michael,

"RETA" stands for Redirection Table.
It is a per-port configurable table of 128 entries that is used by the
RSS filtering feature of Intel 1GbE and 10GbE controllers to select the
RX queue into which to store a received IP packet.
When receiving an IPv4/IPv6 packet, the controller computes a 32-bit
hash on:

   * the source address and the destination address of the IP header of
     the packet,
   * the source port and the destination port of the UDP/TCP header, if any.

Then, the controller takes the 7 lower bits of the RSS hash as an index
into the RETA table to get the RX queue number where to store the packet.

The API of the DPDK includes a function that is exported by Poll Mode
Drivers to configure RETA entries of a given port.

For test purposes, the testpmd application includes the following command

     "port config X rss reta (hash,queue)[,(hash,queue)]"

to configure RETA entries of a port X, with each couple (hash,queue)
contains the index of a RETA entry (between 0 and 127 included) and the
RX queue number (between 0 and 15) to be stored into that RETA entry.

Best regards
Ivan

-- 
Ivan Boule
6WIND Development Engineer