Playing with latest JM authed commits on sch-cake & tc-adv.  Look at the
target values:

root@Router:~# tc -s qdisc change dev ifb4eth0 root cake internet
root@Router:~# tc -s qdisc show dev ifb4eth0
qdisc cake 8008: root refcnt 2 bandwidth 39300Kbit diffserv4 flows rtt
100.0ms noatm overhead 12
 Sent 285837 bytes 1240 pkt (dropped 0, overlimits 144 requeues 0)
 backlog 0b 0p requeues 0
capacity estimate: 10511Kbit
             Tin 0       Tin 1       Tin 2       Tin 3 
  thresh   39300Kbit   36843Kbit   29475Kbit    9825Kbit
  target       5.0ms       5.0ms       5.0ms       5.0ms
interval     100.0ms     100.0ms     100.0ms     100.0ms
Pk-delay         0us        22us         0us         0us
Av-delay         0us         6us         0us         0us
Sp-delay         0us         2us         0us         0us
  pkts             0        1240           0           0
  bytes            0      285837           0           0
way-inds           0           0           0           0
way-miss           0         125           0           0
way-cols           0           0           0           0
  drops            0           0           0           0
  marks            0           0           0           0
Sp-flows           0           0           0           0
Bk-flows           0           2           0           0
last-len           0          82           0           0
max-len            0        1514           0           0

root@Router:~# tc -s qdisc change dev ifb4eth0 root cake rtt 100ms
root@Router:~# tc -s qdisc show dev ifb4eth0
qdisc cake 8008: root refcnt 2 bandwidth 39300Kbit diffserv4 flows rtt
100.0ms noatm overhead 12
 Sent 757689 bytes 2374 pkt (dropped 0, overlimits 464 requeues 0)
 backlog 0b 0p requeues 0
capacity estimate: 5964Kbit
             Tin 0       Tin 1       Tin 2       Tin 3 
  thresh   39300Kbit   36843Kbit   29475Kbit    9825Kbit
  target       6.2ms       6.2ms       6.2ms       6.2ms
interval     100.0ms     100.0ms     100.0ms     100.0ms
Pk-delay         0us       286us         0us         0us
Av-delay         0us        70us         0us         0us
Sp-delay         0us         2us         0us         0us
  pkts             0        2374           0           0
  bytes            0      757689           0           0
way-inds           0           0           0           0
way-miss           0         157           0           0
way-cols           0           0           0           0
  drops            0           0           0           0
  marks            0           0           0           0
Sp-flows           0           0           0           0
Bk-flows           0           2           0           0
last-len           0          82           0           0
max-len            0        1514           0           0

Colour me confused :-)

Kevin