[ adding cake list ] Akshat Kakkar <akshat.1984@xxxxxxxxx> writes: > Cake is expected to handle traffic in 2 steps : > First is on the basis of host > Second is within every host, on the basis of flow > > So, if I limit traffic to 20Mbps shared across 2 host A & B, > Following are various scenarios, expectation and observations > 1. If either A or B is downloading, they will be getting speed of 20Mbps > Observation: Meeting with expectation > > 2. If both A & B downloads (single download each), each will be > getting speed of 20Mbps > Observation: Meeting with expecation but its very jittery (around > 20%), i.e. speed varies from 8Mbps to 12 Mbps. If I use fq_codel speed > is same BUT jitter is very less (around 1%). > > 3. Now if A starts 3 downloads, and B is still having single download, > A each download should be around 3.3 Mbps and B should be around > 10Mbps > Observation: Around 5 Mbps for each download with lot of jitter, i.e. > no advantage of having CAKE!!! > > Linux Kernel 4.20 > For case 3, output of command : tc -s class show dev eno2 > > class htb 1:1 root leaf 8003: prio 1 rate 20000Kbit ceil 20000Kbit > burst 200Kb cburst 1600b > Sent 688474645 bytes 455058 pkt (dropped 0, overlimits 381196 requeues 0) > rate 19874Kbit 1641pps backlog 21196b 14p requeues 0 > lended: 382532 borrowed: 0 giants: 0 > tokens: 1260573 ctokens: -9427 > > class cake 8003:44f parent 8003: > (dropped 3404, overlimits 0 requeues 0) > backlog 9084b 6p requeues 0 > class cake 8003:516 parent 8003: > (dropped 3565, overlimits 0 requeues 0) > backlog 0b 0p requeues 0 > class cake 8003:590 parent 8003: > (dropped 3023, overlimits 0 requeues 0) > backlog 4542b 3p requeues 0 > class cake 8003:605 parent 8003: > (dropped 1772, overlimits 0 requeues 0) > backlog 7570b 5p requeues 0 Could you please share some more details of your setup? The output of `tc -s qdisc show dev eno2`? How are you running the download tests? Is this over the internet, or in a controlled setup? What's your actual line rate? Are you using ingress shaping as well? It looks like you are using HTB for rate limiting on top of CAKE? Why? -Toke
