Redirection Table

Redirection Table

[Michael Quicquaro]

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

Re: Redirection Table

[Ivan Boule]

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

Re: Redirection Table

[Michael Quicquaro]

Thanks for the details.  Can the hash function be modified so that I can
provide my own RSS function?  i.e.  my ultimate goal is to provide RSS that
is not dependent on packet contents.

You may have seen my thread "generic load balancing".  At this point, I'm
realizing that the only way to accomplish this is to let the packets land
where they may (the queue where the NIC places the packet) and distribute
them (to other queues) by having some of the CPU processing devoted to this
task.  Can you verify this?

Regards,
- Michael.


On Mon, Jan 6, 2014 at 10:21 AM, Ivan Boule <ivan.boule-pdR9zngts4EAvxtiuMwx3w@public.gmane.org> wrote:

> 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
>
>

Re: Redirection Table

[Ivan Boule]

On 01/06/2014 05:52 PM, Michael Quicquaro wrote:
> Thanks for the details.  Can the hash function be modified so that I 
> can provide my own RSS function?  i.e.  my ultimate goal is to provide 
> RSS that is not dependent on packet contents.
No, the RSS function is "hard-wired" and only works on IPv4/IPv6 
packets. All other packets are stored in the same queue (0 by default).
You can change the RSS key used by the RSS function to compute the hash 
value.
See the following testpmd command:

    port config X rss-hash-key <80 hexa digits>

to set the 320-bit RSS key of port X.

Best regards,
Ivan

> You may have seen my thread "generic load balancing".  At this point, 
> I'm realizing that the only way to accomplish this is to let the 
> packets land where they may (the queue where the NIC places the 
> packet) and distribute them (to other queues) by having some of the 
> CPU processing devoted to this task.  Can you verify this?
>
> Regards,
> - Michael.
>
>
> On Mon, Jan 6, 2014 at 10:21 AM, Ivan Boule <ivan.boule-pdR9zngts4EAvxtiuMwx3w@public.gmane.org 
> <mailto:ivan.boule-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>> wrote:
>
>     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
>
>


-- 
Ivan Boule
6WIND Development Engineer

Re: Redirection Table

[Stefan Baranoff]

All,

Does this mean that an application looking at traffic in something like an
IP/IP or GRE tunnel with only two endpoints on the tunnels but many clients
behind them must do software load balancing as the packets would IP only
(not TCP/UDP) with the same two addresses?

How much of a penalty is there for crossing processor boundaries in that
case and might a 1 CPU server, while less core dense, actually give better
performance/watt?

Thanks,
Stefan

Sent from my smart phone; people don't make typos, Swype does!
On Jan 7, 2014 3:36 AM, "Ivan Boule" <ivan.boule-pdR9zngts4EAvxtiuMwx3w@public.gmane.org> wrote:

> On 01/06/2014 05:52 PM, Michael Quicquaro wrote:
>
>> Thanks for the details.  Can the hash function be modified so that I can
>> provide my own RSS function?  i.e.  my ultimate goal is to provide RSS that
>> is not dependent on packet contents.
>>
> No, the RSS function is "hard-wired" and only works on IPv4/IPv6 packets.
> All other packets are stored in the same queue (0 by default).
> You can change the RSS key used by the RSS function to compute the hash
> value.
> See the following testpmd command:
>
>    port config X rss-hash-key <80 hexa digits>
>
> to set the 320-bit RSS key of port X.
>
> Best regards,
> Ivan
>
>  You may have seen my thread "generic load balancing".  At this point, I'm
>> realizing that the only way to accomplish this is to let the packets land
>> where they may (the queue where the NIC places the packet) and distribute
>> them (to other queues) by having some of the CPU processing devoted to this
>> task.  Can you verify this?
>>
>> Regards,
>> - Michael.
>>
>>
>> On Mon, Jan 6, 2014 at 10:21 AM, Ivan Boule <ivan.boule-pdR9zngts4EAvxtiuMwx3w@public.gmane.org<mailto:
>> ivan.boule-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>> wrote:
>>
>>     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
>>
>>
>>
>
> --
> Ivan Boule
> 6WIND Development Engineer
>
>

Re: Redirection Table

[Ivan Boule]

On 01/07/2014 02:03 PM, Stefan Baranoff wrote:
>
> All,
>
> Does this mean that an application looking at traffic in something 
> like an IP/IP or GRE tunnel with only two endpoints on the tunnels but 
> many clients behind them must do software load balancing as the 
> packets would IP only (not TCP/UDP) with the same two addresses?
>
Yes, your understanding is correct, when Intel's NICs are used. But some 
other NICs could allow deeper packet analysis.
When NICs only support IPv4/IPv6 RSS, then it is up to the network stack 
on top of the DPDK to provide the best optimal solution in software.

> How much of a penalty is there for crossing processor boundaries in 
> that case and might a 1 CPU server, while less core dense, actually 
> give better performance/watt?
>
This is hard to say. It is likely to partially depend on the 
CPU/memory/bus/ characteristics.
Note that if you consider dedicating a single core to the polling of 
packets received on all ports, then you only need a single RX queue per 
port.
By the way, in such a case, you can still configure RSS on the ports, so 
that the hardware computes the 32-bit RSS hash on each IP packet (it is 
stored into the rte_mbuf structure by the Poll Mode Driver), so that the 
RSS hash can be used in software to speed-up the assignment of IP 
packets to [a subset of] processing cores, if needed.

Regards
Ivan

> Thanks,
> Stefan
>
> Sent from my smart phone; people don't make typos, Swype does!
>
> On Jan 7, 2014 3:36 AM, "Ivan Boule" <ivan.boule-pdR9zngts4EAvxtiuMwx3w@public.gmane.org 
> <mailto:ivan.boule-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>> wrote:
>
>     On 01/06/2014 05:52 PM, Michael Quicquaro wrote:
>
>         Thanks for the details.  Can the hash function be modified so
>         that I can provide my own RSS function?  i.e.  my ultimate
>         goal is to provide RSS that is not dependent on packet contents.
>
>     No, the RSS function is "hard-wired" and only works on IPv4/IPv6
>     packets. All other packets are stored in the same queue (0 by
>     default).
>     You can change the RSS key used by the RSS function to compute the
>     hash value.
>     See the following testpmd command:
>
>        port config X rss-hash-key <80 hexa digits>
>
>     to set the 320-bit RSS key of port X.
>
>     Best regards,
>     Ivan
>
>         You may have seen my thread "generic load balancing".  At this
>         point, I'm realizing that the only way to accomplish this is
>         to let the packets land where they may (the queue where the
>         NIC places the packet) and distribute them (to other queues)
>         by having some of the CPU processing devoted to this task.
>          Can you verify this?
>
>         Regards,
>         - Michael.
>
>
>         On Mon, Jan 6, 2014 at 10:21 AM, Ivan Boule
>         <ivan.boule-pdR9zngts4EAvxtiuMwx3w@public.gmane.org <mailto:ivan.boule-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>
>         <mailto:ivan.boule-pdR9zngts4EAvxtiuMwx3w@public.gmane.org <mailto:ivan.boule-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>>>
>         wrote:
>
>             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
>
>
>
>
>     -- 
>     Ivan Boule
>     6WIND Development Engineer
>


-- 
Ivan Boule
6WIND Development Engineer