[Bloat] CAKE in openwrt high CPU

[Mikael Abrahamsson]

On Mon, 31 Aug 2020, Toke Høiland-Jørgensen wrote:

> And what about when you're running CAKE in 'unlimited' mode?

I tried this:

# tc qdisc add dev eth0 root cake bandwidth 900mbit

This seems fine from a performance point of view (not that high sirq%, 
around 35%) and does seem to limit my upstream traffic correctly. Not sure 
it helps though, at these speeds the bufferbloat problem is not that 
obvious and easy to test over the Internet :)

root at OpenWrt:~# tc -s qdisc
qdisc noqueue 0: dev lo root refcnt 2
  Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
  backlog 0b 0p requeues 0
qdisc cake 8034: dev eth0 root refcnt 9 bandwidth 900Mbit diffserv3 
triple-isolate nonat nowash no-ack-filter split-gso rtt 100.0ms raw 
overhead 0
  Sent 1111772001 bytes 959703 pkt (dropped 134, overlimits 221223 requeues 
179)
  backlog 0b 0p requeues 179
  memory used: 2751976b of 15140Kb
  capacity estimate: 900Mbit
  min/max network layer size:           42 /    1514
  min/max overhead-adjusted size:       42 /    1514
  average network hdr offset:           14

                    Bulk  Best Effort        Voice
   thresh      56250Kbit      900Mbit      225Mbit
   target          5.0ms        5.0ms        5.0ms
   interval      100.0ms      100.0ms      100.0ms
   pk_delay          0us         22us        232us
   av_delay          0us          6us          7us
   sp_delay          0us          4us          5us
   backlog            0b           0b           0b
   pkts                0       959747           90
   bytes               0   1111935437        39440
   way_inds            0        22964            0
   way_miss            0          275            2
   way_cols            0            0            0
   drops               0          134            0
   marks               0            0            0
   ack_drop            0            0            0
   sp_flows            0            3            1
   bk_flows            0            1            0
   un_flows            0            0            0
   max_len             0        68130         3714
   quantum          1514         1514         1514


-- 
Mikael Abrahamsson    email: swmike at swm.pp.se