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Motivated by an observation about steam downloads in the thread Getting
Cake to work better with Steam and similar applications I set up a test
- maybe not the best test ever but interesting results.
Put cake on ifb on PC with netem also on egress/ingress adding 4ms each
way (that's how close I am to steam).
Pretend I have 16mbit atm, though here it's shaped on egress and I am
sending 5 connections 10 sec with netperf and bbr enabled.
This doesn't happen with cubic.
OK so ecn may cure - but people may no know how or want that on.
This issue is that there are a lot of drops causing someone with a
highly asymmetric line to possibly use all upload as (s)ack per packet
is prevalent due to excessive drops.
Here's some pastes same test with target varied (via rtt param)
The 5 connections are from different src ips.
qdisc cake 1: dev ifb0 root refcnt 2 bandwidth 16Mbit diffserv3
dual-srchost rtt 100.0ms atm overhead 40 via-ethernet
Sent 17477050 bytes 11597 pkt (dropped 8476, overlimits 31565 requeues 0)
backlog 0b 0p requeues 0
memory used: 144Kb of 4Mb
capacity estimate: 16Mbit
Bulk Best Effort Voice
thresh 1Mbit 16Mbit 4Mbit
target 18.2ms 5.0ms 5.0ms
interval 113.2ms 100.0ms 10.0ms
pk_delay 0us 6.9ms 0us
av_delay 0us 4.6ms 0us
sp_delay 0us 5us 0us
pkts 0 20073 0
bytes 0 30307578 0
way_inds 0 0 0
way_miss 0 10 0
way_cols 0 0 0
drops 0 8476 0
marks 0 0 0
sp_flows 0 5 0
bk_flows 0 1 0
un_flows 0 0 0
max_len 0 1514 0
qdisc cake 1: dev ifb0 root refcnt 2 bandwidth 16Mbit diffserv3
dual-srchost rtt 200.0ms atm overhead 40 via-ethernet
Sent 17459144 bytes 11584 pkt (dropped 3277, overlimits 26349 requeues 0)
backlog 0b 0p requeues 0
memory used: 161280b of 4Mb
capacity estimate: 16Mbit
Bulk Best Effort Voice
thresh 1Mbit 16Mbit 4Mbit
target 18.2ms 10.0ms 10.0ms
interval 208.2ms 200.0ms 20.0ms
pk_delay 0us 12.7ms 0us
av_delay 0us 10.3ms 0us
sp_delay 0us 11us 0us
pkts 0 14861 0
bytes 0 22420426 0
way_inds 0 0 0
way_miss 0 10 0
way_cols 0 0 0
drops 0 3277 0
marks 0 0 0
sp_flows 0 5 0
bk_flows 0 1 0
un_flows 0 0 0
max_len 0 1514 0
qdisc cake 1: dev ifb0 root refcnt 2 bandwidth 16Mbit diffserv3
dual-srchost rtt 300.0ms atm overhead 40 via-ethernet
Sent 17613408 bytes 11680 pkt (dropped 1574, overlimits 24849 requeues 0)
backlog 0b 0p requeues 0
memory used: 171Kb of 4Mb
capacity estimate: 16Mbit
Bulk Best Effort Voice
thresh 1Mbit 16Mbit 4Mbit
target 18.2ms 15.0ms 15.0ms
interval 303.2ms 300.0ms 30.0ms
pk_delay 0us 13.6ms 0us
av_delay 0us 12.1ms 0us
sp_delay 0us 14us 0us
pkts 0 13254 0
bytes 0 19996444 0
way_inds 0 0 0
way_miss 0 10 0
way_cols 0 0 0
drops 0 1574 0
marks 0 0 0
sp_flows 0 5 0
bk_flows 0 1 0
un_flows 0 0 0
max_len 0 1514 0
qdisc cake 1: dev ifb0 root refcnt 2 bandwidth 16Mbit diffserv3
dual-srchost rtt 400.0ms atm overhead 40 via-ethernet
Sent 17674640 bytes 11720 pkt (dropped 920, overlimits 24270 requeues 0)
backlog 0b 0p requeues 0
memory used: 186624b of 4Mb
capacity estimate: 16Mbit
Bulk Best Effort Voice
thresh 1Mbit 16Mbit 4Mbit
target 20.0ms 20.0ms 20.0ms
interval 400.0ms 400.0ms 40.0ms
pk_delay 0us 16.8ms 0us
av_delay 0us 16.2ms 0us
sp_delay 0us 17us 0us
pkts 0 12640 0
bytes 0 19067520 0
way_inds 0 0 0
way_miss 0 10 0
way_cols 0 0 0
drops 0 920 0
marks 0 0 0
sp_flows 0 5 0
bk_flows 0 1 0
un_flows 0 0 0
max_len 0 1514 0
qdisc cake 1: dev ifb0 root refcnt 2 bandwidth 16Mbit diffserv3
dual-srchost rtt 500.0ms atm overhead 40 via-ethernet
Sent 17614080 bytes 11680 pkt (dropped 613, overlimits 23885 requeues 0)
backlog 0b 0p requeues 0
memory used: 186624b of 4Mb
capacity estimate: 16Mbit
Bulk Best Effort Voice
thresh 1Mbit 16Mbit 4Mbit
target 25.0ms 25.0ms 25.0ms
interval 500.0ms 500.0ms 50.0ms
pk_delay 0us 18.6ms 0us
av_delay 0us 17.1ms 0us
sp_delay 0us 19us 0us
pkts 0 12293 0
bytes 0 18542162 0
way_inds 0 0 0
way_miss 0 10 0
way_cols 0 0 0
drops 0 613 0
marks 0 0 0
sp_flows 0 5 0
bk_flows 0 1 0
un_flows 0 0 0
max_len 0 1514 0
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