Re: [Bloat] Tuning fq_codel: are there more best practices for slow connections? (<1mbit)

[Y <intruder_tkyf@yahoo.fr>]

Hi ,Moeller.

Fomula of target is 1643 bytes / 810kbps = 0.015846836.

It added ATM linklayer padding.

16ms plus 4ms as my sence :P

My connection is 12mbps/1mbps ADSL PPPoA line.
and I set 7Mbps/810kbps for bypass router buffer.

I changed Target 27ms Interval 540ms as you say( down delay plus upload 
delay).

It works well  , now .
Thank you.

Yutaka.

On 2017年11月02日 17:25, Sebastian Moeller wrote:
> Hi Y.
>
>
>> On Nov 2, 2017, at 07:42, Y <intruder_tkyf@yahoo.fr> wrote:
>>
>> hi.
>>
>> My connection is 810kbps( <= 1Mbps).
>>
>> This is my setting For Fq_codel,
>> quantum=300
>>
>> target=20ms
>> interval=400ms
>>
>> MTU=1478 (for PPPoA)
>> I cannot compare well. But A Latency is around 14ms-40ms.
> 	Under full saturation in theory you would expect the average latency to equal the sum of upstream target and downstream target (which in your case would be 20 + ???) in reality I often see something like 1.5 to 2 times the expected value (but I have never inquired any deeper, so that might be a measuring artifact)...
>
> Best Regards
>
>
>> Yutaka.
>>
>> On 2017年11月02日 15:01, cloneman wrote:
>>> I'm trying to gather advice for people stuck on older connections. It appears that having dedictated /micromanged tc classes greatly outperforms the "no knobs" fq_codel approach for connections with  slow upload speed.
>>>
>>> When running a single file upload @350kbps , I've observed the competing ICMP traffic quickly begin to drop (fq_codel) or be delayed considerably ( under sfq). From reading the tuning best practices page is not optimized for this scenario. (<2.5mbps)
>>> (https://www.bufferbloat.net/projects/codel/wiki/Best_practices_for_benchmarking_Codel_and_FQ_Codel/) fq_codel
>>>
>>> Of particular concern is that a no-knobs SFQ works better for me than an untuned codel ( more delay but much less loss for small flows). People just flipping the fq_codel button on their router at these low speeds could be doing themselves a disservice.
>>>
>>> I've toyed with increasing the target and this does solve the excessive drops. I haven't played with limit and quantum all that much.
>>>
>>> My go-to solution for this would be different classes, a.k.a. traditional QoS. But ,  wouldn't it be possible to tune fq_codel punish the large flows 'properly' for this very low bandwidth scenario? Surely <1kb ICMP packets can squeeze through properly without being dropped if there is 350kbps available, if the competing flow is managed correctly.
>>>
>>> I could create a class filter by packet length, thereby moving ICMP/VoIP to its own tc class, but  this goes against "no knobs" it seems like I'm re-inventing the wheel of fair queuing - shouldn't the smallest flows never be delayed/dropped automatically?
>>>
>>> Lowering Quantum below 1500 is confusing, serving a fractional packet in a time interval?
>>>
>>> Is there real value in tuning fq_codel for these connections or should people migrate to something else like nfq_codel?
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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