From: Y <intruder_tkyf@yahoo.fr>
To: bloat@lists.bufferbloat.net
Subject: Re: [Bloat] Tuning fq_codel: are there more best practices for slow connections? (<1mbit)
Date: Fri, 3 Nov 2017 01:53:50 +0900 [thread overview]
Message-ID: <e632c581-ede3-2ea0-e8cb-8870fda6693d@yahoo.fr> (raw)
In-Reply-To: <a67b5f5c-539b-502a-76bc-e57df2dc8458@pollere.com>
Hi , Kathleen.
Fomula of target is 1643 bytes / 810kbps = 0.015846836.
It added ATM linklayer padding.
On 2017年11月03日 01:33, Kathleen Nichols wrote:
> On 11/2/17 1:25 AM, 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)...
> An MTU packet would cause 14.6ms of delay. To cause a codel drop, you'd
> need to have a queue of more than one packet hang around for 400ms. I
> would suspect if you looked at the dynamics of the delay you'll see it
> going up and down and probably averaging to something less than two
> packet times. Delay vs time is probably going to be oscillatory.
>
> Is the unloaded RTT on the order of 2-300 ms?
(When I do speedtest upload with ping to 8.8.8.8)
Ping RTT is around 30ms-80ms.
Avarage is around 40ms-50ms.
There is not 100ms over delay.
>
Delay vs time is probably going to be oscillatory.
yes :)
>> 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?
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> Bloat mailing list
>>>>
>>>> Bloat@lists.bufferbloat.net
>>>> https://lists.bufferbloat.net/listinfo/bloat
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next prev parent reply other threads:[~2017-11-02 16:53 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-02 6:01 cloneman
2017-11-02 6:42 ` Y
2017-11-02 8:25 ` Sebastian Moeller
2017-11-02 16:33 ` Kathleen Nichols
2017-11-02 16:53 ` Y [this message]
2017-11-02 16:58 ` Y
2017-11-02 20:31 ` Sebastian Moeller
2017-11-03 0:31 ` Yutaka
2017-11-03 9:53 ` Sebastian Moeller
2017-11-03 10:10 ` Yutaka
2017-11-03 10:31 ` Sebastian Moeller
2017-11-03 10:51 ` Yutaka
2017-11-02 7:11 ` Jonathan Morton
2017-11-02 8:23 ` Sebastian Moeller
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