Hi Loganaden,
> On Jul 19, 2016, at 10:09 , Jonathan Morton <[email protected]> wrote:
>
>
>> On 19 Jul, 2016, at 07:29, Loganaden Velvindron <[email protected]> wrote:
>>
>> I've been playing with fq_codel on 3g internet connection. the 3g
>> internet box has no bridge mode, and just forwards every packet to the
>> Openwrt router.
>>
>> Here are the results without:
>> http://www.dslreports.com/speedtest/4470186
>>
>> And here is the result with fq_codel on and 300 ms target latency:
>>
>> http://www.dslreports.com/speedtest/4470286
>>
>> Is there anything that could be done to get the rating up to A+ by
>> tweaking the code ?
>
> You say fq_codel, rather than Cake. Presumably it is paired with some sort
> of shaper, such as HTB? This is important, because I think the shaper is
> influencing part of your results.
>
> On downstream, you have one high latency sample (750ms) in the middle of a
> series of reasonable ones (250ms). This implies a momentary glitch in your
> connection, which isn’t unusual with wireless links. Re-measuring might
> eliminate it.
>
> On upstream, you have two very high latency samples at the *beginning* of the
> run, which then clear out to approximately the baseline latency. This is a
> classic sign that your shaper is letting a burst of traffic through before
> actually starting to control it, which is typical behaviour for token-bucket
> shapers. That initial burst collects in the dumb queue of your 3G modem and
> takes time to drain away.
>
> Cake uses a shaper carefully designed to *not* burst in that manner, while
> still maintaining full throughput regardless of timer resolution and latency.
> Using Cake instead of fq_codel+HTB will therefore probably improve your
> upload characteristics.
I believe that the way sqm-scripts simple.qos and simplest.qos use the
HTB shaper are not subject to this specific issue (we do not configure/allow
HTB to burst at all). Looking at a number of my speed tests seems to support
this observation (https://www.dslreports.com/speedtest/636817 simplest.qos,
HTB+fq_codel no initial bursting).
Best Regards
Sebastian
>
> - Jonathan Morton
>
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