dualq L queue causes under-utilization for bursty traffic

[pete@…]

In testing we noticed that the low latency queue's marking strategy leads to under-utilization for bursty traffic, with close to a 90% throughput reduction using simulated wifi burstiness. An explanation is here:

​https://github.com/heistp/sce-l4s-ect1#ultra-low-delay

The table of results is here (see table with dualpi2 as qdisc):

​https://github.com/heistp/sce-l4s-ect1#scenario-5-wifi-burstiness