Can you clarify what you mean by a "round" here, please? Do you mean a complete round-robin pass of clients (or whatever segmentation method is used) in the fair queue?
https://arxiv.org/pdf/1703.00064.pdf
Before/After on an ath10k chip here:
https://forum.openwrt.org/t/aql-and-the-ath10k-is-lovely/590...
This among other things made codel's head drop aqm safe and stable enough to deploy.
Paper: https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=8469111
from: https://datatracker.ietf.org/doc/html/rfc8290
The step that moves an empty queue from the list of new queues to the end of the list of old queues before it is removed is crucial to prevent starvation. Otherwise, the queue could reappear (the next time a packet arrives for it) before the list of old queues is visited; this can go on indefinitely, even with a small number of active flows, if the flow providing packets to the queue in question transmits at just the right rate. This is prevented by first moving the queue to the end of the list of old queues, forcing the scheduler to service all old queues before the empty queue is removed and thus preventing starvation.
The resulting migration of queues between the different states is
summarised in the state diagram shown in Figure 1. Note that both
the new and old queue states can additionally have arrival and
dequeue events that do not change the state; these are omitted in the
figure.
+-----------------+ +------------------+
| | Empty | |
| Empty |<---------------+ Old +----+
| | | | |
+-------+---------+ +------------------+ |
| ^ ^ |Credits
|Arrival | | |Exhausted
v | | |
+-----------------+ | | |
| | Empty or | | |
| New +-------------------+ +-------+
| | Credits Exhausted
+-----------------+
Figure 1: Partial State Diagram for Queues between Different States