Hi Kevin,
so the way codel is designed target is best understood as a function of
interval (allowing 5-10% of interval as standing queue allows a fine trade-off
between bandwidth utilization and latency under load increase).
Now, interval is basically akin to the time you are willing to give a flow to
react to signals, it should be in the same order of magnitude as the path RTT.
Now reducing the bandwidth allocation for a traffic class will increase its
saturation load RTT and hence increasing the target seems justified; target
just follows along due to still wanting a reasonable bandwidth/latency
trade-off.
So in short these scale the shaper to work well under loaded conditions. But
Jonathan & Toke will be able to give the real explanation ;)
Best Regards
Sebastian
> On Jun 24, 2020, at 16:33, Kevin Darbyshire-Bryant
> <[email protected]> wrote:
>
> Genuine question. For the reduced bandwidth tins in diffserv3/4/8 a
> different rate and hence different target & interval values are also
> calculated. I get why a target/interval calculation is desirable for the
> ‘main’ tin - this forms a ‘best case’ of how long each byte takes to transmit
> and is fundamental to the shaper. What I’m less clear on is why increased
> targets & intervals are used for the reduced threshold tins.
>
> To my mind it means those tins can be more ‘bursty’ before codel jumps on
> them. That’s possibly ok on an egress path but I’m not so convinced on an
> ingress path.
>
> Please point out the error in my thinking!
>
>
> Cheers,
>
> Kevin D-B
>
> gpg: 012C ACB2 28C6 C53E 9775 9123 B3A2 389B 9DE2 334A
>
> _______________________________________________
> Cake mailing list
> [email protected]
> https://lists.bufferbloat.net/listinfo/cake
_______________________________________________
Cake mailing list
[email protected]
https://lists.bufferbloat.net/listinfo/cake
