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Linux/AM5726: Ethernet traffic control hardware queues

Expert 1210 points

Replies: 11

Views: 1591

Part Number: AM5726

Tool/software: Linux

Am5726

Processor SDK Linux 3.3.0.4 RT

Kernel 4.4.41 (RealTime)

 

We would like to use the mqprio qdisc to get important traffic with very low jitter (ideally <200us for a packet every 4ms) and additionally TCP traffic for e.g. showing pictures in a UI (high volume). Apart from throtteling the data from the application side, we thought that tc qdisc mqprio would be the ideal solution, so we can filter the important traffic to the highest priority hw queue.

 

However, this does not work, when we do 

tc qdisc add dev eth1 root handle 1: mqprio num_tc 3 map 2 2 1 1 2 2 2 2 2 2 2 2 2 2 2 2 queues 1@0 1@1 2@2 hw 1

we get “RTNETLINK answers: Operation not supported”

 

A patch suggested at  http://patches.linaro.org/patch/136371/ seems not to be applicable to that kernel version.

 

Are there ways to configure the linux kernel so that this can be made functional?

  • In reply to Kevin Schuster:

    Hi Kevin,

    I will need to research your question on enabling traffic control. There has been some done on a current SDK or the future SDK that I will need to look into to see if this help with what you are trying to do. Is it possible to move to a later RT kernel by any chance?

    Best Regards,
    Schuyler
  • In reply to Schuyler Patton:

    While we could introduce individual patches carefully, we would be glad to stay with the Kernel from the 3.3.0.4 SDK due to achieved test progress

  • In reply to Kevin Schuster:

    Ping?
  • In reply to Kevin Schuster:

    Hi,
    I am still researching this and will report back tomorrow or Friday.
    Best Regards,
    Schuyler
  • In reply to Schuyler Patton:

    Hey Schuyler, still no news for this issue?
  • In reply to Kevin Schuster:

    Hi,

    After an internal discussion with TI internal Linux developers the conclusion is that it is not recommended or could be supported by TI to try back port patches to the kernel version you are on to support the mqprio feature which you see in the patch adding that support. There has been significant development to the kernel that support mq, mqprio and other necessary features. The support that is going into the cpsw driver was the work that TI is doing now that is to take advantage of that support that has been added to the kernel by the community.

    Best Regards,
    Schuyler
  • In reply to Schuyler Patton:

    So where can we get more informations about that topic? You think a newer kernel version would include a solution for us?
  • In reply to Kevin Schuster:

    Hi,

    I am looking into seeing that would be a solution. A discussion with the development team today indicated that the support is still being merged with mainline.

    Best Regards,
    Schuyler
  • In reply to Schuyler Patton:

    So I could try with the latest SDK or doesnt contain it the latest kernel version?

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