[Codel] [Bloat] Exploring the potential of codel, fq_codel, and qfq

[Eric Dumazet]

On Wed, 2012-05-16 at 00:20 -0700, Dave Taht wrote:

> With ecn:
> 
> 64 bytes from 149.20.63.18: icmp_req=46 ttl=64 time=10.6 ms
> 64 bytes from 149.20.63.18: icmp_req=47 ttl=64 time=5.66 ms
> 64 bytes from 149.20.63.18: icmp_req=48 ttl=64 time=11.8 ms
> 64 bytes from 149.20.63.18: icmp_req=49 ttl=64 time=3.68 ms
> 64 bytes from 149.20.63.18: icmp_req=50 ttl=64 time=10.2 ms
> 64 bytes from 149.20.63.18: icmp_req=51 ttl=64 time=12.8 ms
> 64 bytes from 149.20.63.18: icmp_req=52 ttl=64 time=2.62 ms
> 64 bytes from 149.20.63.18: icmp_req=53 ttl=64 time=7.86 ms
> 
> TCP_RR: 102
> 
> All of these sets of results need more rigor attached.

On TCP_RR pure workload, you have one packet in flight per flow.

ECN adds nothing in this case, only that no 'drops' occurs at all.

It might be good to change fq_codel to perform ECN mark only if flow
queue has more packets.

If not, plain drop.