[dpdk-users] qos: traffic shaping at queue level

Nikhil Jagtap nikhil.jagtap at gmail.com
Fri Sep 30 06:12:06 CEST 2016

Can someone please answer my queries?
I tried using queue weights to distribute traffic-class bandwidth among the
child queues, but did not get the desired results.


On 27 September 2016 at 15:34, Nikhil Jagtap <nikhil.jagtap at gmail.com>

> Hi,
> I have a few questions about the hierarchical scheduler. I am taking a
> simple example here to get a better understanding.
> Reference example:
>   pipe rate = 30 mbps
>   tc 0 rate = 30 mbps
>   traffic-type 0 being queued to queue 0, tc 0.
>   traffic-type 1 being queued to queue 1, tc 0.
>   Assume traffic-type 0 is being received at the rate of 25 mbps.
>   Assume traffic-type 1 is also being received at the rate of 25 mbps.
> Requirement:
>   To limit traffic-type 0 to (CIR =  5 mbps, PIR = 30 mbps), AND
>       limit traffic-type 1 to (CIR = 25 mbps, PIR = 30 mbps).
> The questions:
> 1) I understand that with the scheduler, it is possible to do rate
> limiting only at the sub-port and pipe levels and not at the individual
> queue level. Is it possible to achieve rate limiting using the notion of
> queue weights? For the above example, will assigning weights in 1:5 ratio
> to the two queues help achieve shaping the two traffic-types at the two
> different rates?
> 2) In continuation to previous question: if queue weights don't help,
> would it be possible to use metering to achieve rate limiting? Assume we
> meter individual traffic-types (using CIR-PIR config mentioned above)
> before queuing it to the scheduler queues. So to achieve the respective
> queue rates, the dequeuer would be expected to prioritise green packets
> over yellow.
> Looking into the code, the packet color is used as an input to the dropper
> block, but does not seem to be used anywhere in the scheduler. So I guess
> it is not possible to prioritise green packets when dequeing?
> Regards,
> Nikhil

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