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doc:howto:packet.scheduler:sch_codel [2012/11/22 16:27]
doc:howto:packet.scheduler:sch_codel [2013/08/10 20:45] (current)
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 +====== CoDel - The Controlled-Delay Active Queue Management algorithm ======
 +  * [[http://​​source/​net/​sched/​sch_codel.c|Source Code]]
 +  * [[http://​​projects/​codel/​wiki|Buffer Bloat]]
 +Explanations for the average person:
 +  * This Video: [[http://​​watch?​v=y5KPryOHwk8|YT 41minutes]] at Time point ~ 21:00 explains CoDel
 +  * it also explains [[doc/​howto/​packet.scheduler/​sch_fq_codel|Fair Queue CoDel]]
 +  * but is does not explain [[doc/​howto/​packet.scheduler/​sch_hfsc|HFSC]]!!!
 +  * measure the latency in the queue (from ingress to egress, via time stamping on entry and checking the timestamp on exit
 +  * when latency exceeds tartget, think about dropping a packet
 +  * after latency exceeds target, drop a packet at the HEAD of the queue (not the tail!)
 +  * if that does not fix it, after a shorter interval (inverse sqrt), drop the net packet sooner, again at the HEAD
 +  * keep decreasing the interval between drops until the latency in the queue drops below target
 +  * we start with 100ms at the interval of the estimate and 5ms as the target (for 4Mbit/s and up) 10Gbig/s needs a smaller target.
 +  * below 4Mbit/s ... well, we don't know