[Cerowrt-devel] AQM and ADSL

Sebastian Moeller moeller0 at gmx.de
Wed Aug 14 11:09:23 EDT 2013 

Hi Fred,


On Aug 14, 2013, at 16:28 , Fred Stratton <fredstratton at imap.cc> wrote:

> 
> On 14 Aug 2013, at 15:18, Sebastian Moeller <moeller0 at gmx.de> wrote:
> 
>> Hi Fred,
>> 
>> 
>> On Aug 14, 2013, at 15:37 , Fred Stratton <fredstratton at imap.cc> wrote:
>> 
>>> 
>>> On 14 Aug 2013, at 14:31, Sebastian Moeller <moeller0 at gmx.de> wrote:
>>> 
>>>> Hi Fred,
>>>> 
>>>> 
>>>> On Aug 14, 2013, at 14:01 , Fred Stratton <fredstratton at imap.cc> wrote:
>>>> 
>>>>> 
>>>>> On 14 Aug 2013, at 12:42, Sebastian Moeller <moeller0 at gmx.de> wrote:
>>>>> 
>>>>>> Hi Fred,
>>>>>> 
>>>>>> 
>>>>>> On Aug 13, 2013, at 21:40 , Fred Stratton <fredstratton at imap.cc> wrote:
>>>>>> 
>>>>>>> (apologies for wrecking the list, and introducing email addresses in error)
>>>>>>> 
>>>>>>> 
>>>>>>> Begin forwarded message
>>>>>>>> On 13 Aug 2013, at 19:53, Sebastian Moeller <moeller0 at gmx.de> wrote:
>>>>>>>> 
>>>>>>>>> H Fred
>>>>>>>>> On Aug 13, 2013, at 17:28 , Fred Stratton <fredstratton at imap.cc> wrote:
>>>>>>>>> 
>>>>>>>>>> I have been experimenting with the two sets of modified sets of scripts and AQM panels. Thank you for constructing them.
>>>>>>>>> 
>>>>>>>>> 	Thanks for testing...
>>>>>>>>> 
>>>>>>>>>> 
>>>>>>>>>> To mention the string ''for ATM choose' is repeated erroneously in the extended panel.
>>>>>>>>> 
>>>>>>>>> 	Fixed… I will try to test whether it actually works before sending the next version...
>>>>>>>>> 
>>>>>>>>>> 
>>>>>>>>>> The scripts work.
>>>>>>>>>> 
>>>>>>>>>> The link layer giving best results is ethernet.
>>>>>>>>> 
>>>>>>>>> 	What and how did you measure? Using "use HTB's private mechanism for linklayer and overhead" or "Use tc's stab mechanism for linklayer and overhead"? A little browsing of the kernel source makes me believe that the HTB version is fully busted and will not do anything at all (so I would have imagined adel atm and ethernet to behave the same). I am thinking about how to test whether a link layer adjustment works or not.
>>>>>>>> 
>>>>>>>> Ein Fehler. I had both chosen. They are mutually exclusive options.  2 days of testing lost. Shall restart.
>>>>>> 
>>>>>> 	I will try to fix the AQM scripts to make these two mutually exclusive. That said, the HTB internal implementation does not seem to work at all, so enabling both should be equivalent to just enabling stab. In my quick and dirty testing (using netsurf-wrapper, which I got working on macosx 10.8) it looks like activating both actually should work. BTW I am looking for an open netsurf server in Europe anybody any ideas?
>>>>> 
>>>>> I am actually getting better results from htb than td-stab at present.
>>>> 
>>>> 	Then I will have to test an compare the RRUL performance for stab-linklayeradjustments (loa), htb-lla, no-lla, no-shaping at all, at 50% of link rate and at say 80% of link rate and see which performs best. Alas I need a closer netperf 2.6.0 net server binary than the ones in NY and CA. So far I am failing to find a windows binary I could run on one of the machines in the lab…
>>>> 	How do you measure currently? I would love to run the same tests to figure out what is up with the two loa methods.
>>> 
>>> Netalyzr, for all its deficiencies.
>> 
>> 	Ah, so you are basically testing the maximum depth of the ge00 uplink fq_codels, which is set at 600 at the moment. You could test this by changing the value in egress() if simple.qos
>> 
>> $TC qdisc add dev $IFACE parent 1:11 handle 110: $QDISC limit 600 $NOECN `get_quantum 300` `get_flows ${PRIO_RATE}`
>> $TC qdisc add dev $IFACE parent 1:12 handle 120: $QDISC limit 600 $NOECN `get_quantum 300` `get_flows ${BE_RATE}`
>> $TC qdisc add dev $IFACE parent 1:13 handle 130: $QDISC limit 600 $NOECN `get_quantum 300` `get_flows ${BK_RATE}`
>> 
>> to 
>> 
>> $TC qdisc add dev $IFACE parent 1:11 handle 110: $QDISC limit 300 $NOECN `get_quantum 300` `get_flows ${PRIO_RATE}`
>> $TC qdisc add dev $IFACE parent 1:12 handle 120: $QDISC limit 300 $NOECN `get_quantum 300` `get_flows ${BE_RATE}`
>> $TC qdisc add dev $IFACE parent 1:13 handle 130: $QDISC limit 300 $NOECN `get_quantum 300` `get_flows ${BK_RATE}`
>> 
>> and the reported buffering will get lower… I assume that netalyzr only complains about the uplink and the downlink is okay? Setting limit higher will make netalyzr more unhappy (up to a certain number over which netalyzr will get happy again). I assume netalyzr simply uses an inelastic UDP load of a fixed bandwidth tries to fill buffers until dropping occurs and deduces the size of the buffer from the amount of data that passed before dropping, if all fits into the buffer nothing needs dropping and hence netalyzr should be happy even though the buffers just got more bloated. 
>> 
>> 	You could also try http://loki10.mpi-sws.mpg.de/bb/bb.php for that kind of a test which IIRC uses higher bandwidth probes.
>> 
>> 
>> But we have been there in the past, see https://lists.bufferbloat.net/pipermail/cerowrt-devel/2012-August/000418.html the critical test is to see whether a concurrent ping or ssh session stays responsive in spite of the netalyzr probe… And interestingly in the old e-mail cited, no AQM defaulted to 500ms uplink delay, the cable modems buffer was simply not enormously oversized to begin with… 
>> 
>> 	Could you share the netalyzr numbers for no AQM, AQM with HTB and AQM with stab, in any way? And in case you can run this how do the ping statistics (example:
>> 
>> --- www.heise.de ping statistics ---
>> 10 packets transmitted, 10 packets received, 0.0% packet loss
>> round-trip min/avg/max/stddev = 5.813/6.120/6.619/0.213 ms
>> 
>> of a concurrent "ping -c 1000 IPADDRESS.OF.NEAREST>ISPHOST" look, especially the max and stddev values could be interesting…
> 
> There will be a delay.

	I do not think that these measurements will be too revealing anyways, netalyzr is a good test for simple pfifo or pfifo_fast discs, but not too interesting for fq_codel. In case you stick to using netalyzr concurrent ping data might be nice, but better switch to a different latency probe.


> 
> have installed netsurf-wrapper etc, but am having difficulty with the switches.


	Ah, so I so far simply used 
./netperf-wrapper -l 60 -H snapon.lab.bufferbloat.net rrul -p all_scaled

to at least get pretty pictures for my quick and dirty testing. The -l NN controls the duration of the test, the -H the host, I found that both snapon.lab.bufferbloat.net and icei.org seem to be open netsurf servers (as Dave announced earlier this year), I do not know whether these are supposed to be used by everyone or not (and it would be nice to have a net server closer in Europe anyways). 

I hope this gets you going…

Best
	Sebastian


> 
> 
>> 
>> 
>>>> 
>>>> 
>>>>>> 
>>>>>> 
>>>>>>>>> 
>>>>>>>>> 
>>>>>>>>>> Pinging severs whilst running Netalyzr has no effect.
>>>>>>>>> 
>>>>>>>>> 	Not being a native english speaker cloud you be more explicit, please. Was the ping RTT affected by the concurrent netalyzr run (especially up- and download testing)? Did you get netsurf-wrapper to work on ubuntu? 
>>>>>>>> 
>>>>>>>> You did not understand because I explained what I did, and I did the wrong thing.
>>>>>>>> 
>>>>>>>> Not done properly. Will retry. Netsurf-wrapper will not compile. I am going to move to a more recent version of Ubuntu.
>>>>>> 
>>>>>> 	Interesting, I managed to install it under 64bit Ubuntu 12.04 in a virtual machine, using the packages Toke supplied. I just added http://archive.tohojo.dk/ to "Software Sources" in "Update Manager" than I could use the "Synaptic Package Manager" to install netperf and netperf-wrapper from Toke's repository; so I guess no ned to compile anything. (Under maces however installing netsurf-wrapper was slightly more involved as the recommended way via pip did not work, so I had to download the netperf-wrapper repository from https://github.com/tohojo/netperf-wrapper and the cd into the downloaded directory and issue "sudo python2.7 ./setup.py install" there and I had to symplink python2.7 to python2, but after that it also worked).
>>>>>> 	Just as a illustration what to expect, please find attached the RRUL results with stab based AQM und without any AQM; clearly fq_codel improves the ping RTTs a lot, so AQM works. Alas, I did not repeat this test with shaping enabled but no link layer adjustments or with the HTB link layer adjustments, so can not really tell, whether RRUL is sensitive enough to show the effects of link layer adjustments or not (my bet is on not as RRUL in my understanding uses large packets while the ATM quantization effects are strongest for small packets). I might try to do this tonight or when I get around to do it…
>>>>>> 	I would be really curious to see such plots from your setup for comparison.
>>>>> 
>>>>> Will try your suggestion for Ubuntu.
>>>>> 
>>>>> 
>>>>>> 
>>>>>> <figure_5.png><figure_6_like_5_noAQM.png>
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>>>>> 
>>>>>>>>> 
>>>>>>>>>> 
>>>>>>>>>> The tone buckets of the phone signal are translated into ATM packets by the DSP in the 2 Wire 2700. I have no idea what this closed source BSD implementation does to the packets before they are sent to CeroWRT.
>>>>>>>>> 
>>>>>>>>> 
>>>>>>>>> 
>>>>>>>>>> 
>>>>>>>>>> I am using 3.10.2-1, as I cannot get the latest version to install with sys upgrade.
>>>>>>>> 
>>>>>>>> I was trying 3.10.5-1 
>>>>>> 
>>>>>> 	Ah, good, I might try 3.10.6-1 then directly in tftp mode. Does anyone know how much time I have between releasing the reset button and starting the tftp transfer? 
>>>>>> 
>>>>> sys upgrade does not work with the latest build. If you have to press the recovery button during restart, I cannot se tftp. Does anyone know of programmatic alternatives?
>>>> 
>>>> 	Ah, then is is going to be TFTP I guess. What do you mean by "If you have to press the recovery button during restart, I cannot se tftp"? Does the "reboot-with-reset-button-pressed" not work after a failed sys upgrade?
>>> 
>>> I  cannot press the reset button whilst restart in the router. The procedure works, but I cannot do it.
>> 
>> 	Ah, good, then I will risk an upgrade. While needing a stool or ladder I should be able to actually press the button during restart…
> 
> The procedure SHOULD work. I have not tested it.
>> 
>>> I am looking for an alternative. There will be a programmatic approach to enter kernel mode.
>> 
>> Best Regards
>> 	Sebastian
>> 
>> 
>>>> 
>>>> Best Regards
>>>> 	Sebastian
>>>> 
>>>> 
>>>>>> Best
>>>>>> 	Sebastian
>>>>>> 
>>>>>> 
>>>>>>>> 
>>>>>>>> DT has taken to stealth with his releases.
>>>>>>>> 
>>>>>>>>> 
>>>>>>>>> 	So 3.10.6-1 fails with sysupgrade?
>>>>>>>>> 
>>>>>>>>> best
>>>>>>>>> 	Sebastian
>>>>>>>>> 
>>>>>>>>>> 
>>>>>>>>>> _______________________________________________
>>>>>>>>>> Cerowrt-devel mailing list
>>>>>>>>>> Cerowrt-devel at lists.bufferbloat.net
>>>>>>>>>> https://lists.bufferbloat.net/listinfo/cerowrt-devel
>>>>>>>>> 
>>>>>>>> 
>>>>>>> 
>>>>>>> _______________________________________________
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>>>>>>> Cerowrt-devel at lists.bufferbloat.net
>>>>>>> https://lists.bufferbloat.net/listinfo/cerowrt-devel
>>>>>> 
>>>>> 
>>>>> _______________________________________________
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>>>>> Cerowrt-devel at lists.bufferbloat.net
>>>>> https://lists.bufferbloat.net/listinfo/cerowrt-devel
>>>> 
>>> 
>> 
> 
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