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

[Nikhil Jagtap <nikhil.jagtap@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