[Codel] [Cake] openwrt build available with latest cake and fq_pie
chromatix99 at gmail.com
Sun Jun 14 14:07:21 EDT 2015
> On 14 Jun, 2015, at 20:38, Dave Taht <dave.taht at gmail.com> wrote:
>> Every time Codel triggers the dropping state, it will mark or drop at least one packet, and increment count by that number. With count decremented only by 1 on recovery, it will effectively remain constant *if*, by some miracle, the queue empties before the second signal was sent; it cannot decrease between episodes unless it resets or wraps.
> It aint a miracle, it is hopefully within an rtt.
No, it is *at minimum* one RTT. It takes that long for the congestion signal to reach the receiver, be reflected back to the sender, the sender’s reaction to *begin to* appear at the queue. Then the queue *starts* to empty, if the signal is what’s required to make it do so.
> When resuming the drop phase of codel, it is almost *already* too late
> to catch that burst incurring the latency.
Yes, but that’s what FQ is for. And ELR, if we ever get that properly started.
> Sometimes I think we need to do away with the count idea and measure
> slopes of curves instead, and "harmonics”.
> Is there any reason why the decrease couldn't be some sort of decay?
> I.e. a function of how long ago the drop state was exited?
Such things are theoretically possible, but require further thought to determine how best to do them.
- Jonathan Morton
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