From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net (mout.gmx.net [212.227.15.15]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (Client CN "mout.gmx.net", Issuer "TeleSec ServerPass DE-1" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id DB70521F184 for ; Sun, 25 Aug 2013 14:40:52 -0700 (PDT) Received: from hms-beagle-2.home.lan ([79.229.225.62]) by mail.gmx.com (mrgmx103) with ESMTPSA (Nemesis) id 0LlleO-1Vn2np20ZM-00ZOvG for ; Sun, 25 Aug 2013 23:40:49 +0200 Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 6.5 \(1508\)) From: Sebastian Moeller In-Reply-To: Date: Sun, 25 Aug 2013 23:40:48 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: <281A5B67-D0A2-4671-BA1F-3A778CEE613E@gmx.de> References: <56B261F1-2277-457C-9A38-FAB89818288F@gmx.de> <2148E2EF-A119-4499-BAC1-7E647C53F077@gmx.de> <03951E31-8F11-4FB8-9558-29EAAE3DAE4D@gmx.de> <9A9B094D-CA07-48B0-85FE-FA7C759FEDE3@gmx.de> <5BEF0C7C-C2F4-45A9-9FF2-E32A05B8D67B@gmx.de> <8CD72282-88CB-43FD-84EF-574DDB23F0AB@gmx.de> <0886582B-E46C-4F93-A9E5-C45A81C32AEA@imap.cc> <8AFDEBD8-54C9-46B6-8CBE-5CD4242A2765@imap.cc> To: Dave Taht X-Mailer: Apple Mail (2.1508) X-Provags-ID: V03:K0:rzVhRhYve+5EEHChLBfBW0wutf6cj46iYX2rDj9+altZoasRDs8 zKbvNpCcooTGoZH+JD1Tw87f8/DMwoSV/Hx6SP/ho/MN84Twz2Wsfcm48K2gIiyiIV45C6i Xe6xTM051NNCGtdgvzUXH3Vm/lZ1CNUEFkcsD/xP9laf0UfoNC6Zhra1BIpENZ/4nc7knsB sTLTITG4+wdmw4G/fpPaA== Cc: "cerowrt-devel@lists.bufferbloat.net" Subject: Re: [Cerowrt-devel] some kernel updates X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 25 Aug 2013 21:40:53 -0000 Hi Dave hi list, On Aug 25, 2013, at 22:28 , Dave Taht wrote: > The rule of thumb for fixing downloads is to start at 85% of your = rated dl and try to get to 95%. It is unfortunately very subject to the = RTT of your last hop, which on DSL is quite a lot, so I would be = surprised if you could crack 90%. Cutting it by 50% is a bit much tho! Well, 50% is close to the worst case for ATM, if you need two = ATM cells instead of 1. So starting at 50% rules out the ATM = encapsulation. So starting at 50% is not a bad idea, staying there = though would be ;) . Start at 50% to gat a glimpse of what the = connection should be able to do and then bisect your way up again... > (It would, as always, be best if the provider used something fq_codel = like on their rate limiter, not yours).=20 That would be sweet. My hopes for Germany are quite low, but I = have heard about the UK it might be in the books (PPPoA or IPoA, and = baby jumbo frames to allow a MTU of 1500 in spite of PPP overhead are = good signs in my book) >=20 > but I'm glad to hear you are making progress! Yepp, I hope that reduced downlink rates make Fred's connection = useable again. Best Regards Sebastian >=20 >=20 > On Sun, Aug 25, 2013 at 12:08 PM, Fred Stratton = wrote: > That is very helpful. >=20 > With a sync rate of about 12000 kbits/s, and a download rate of about = 10900 kbits/s. I have set the download rate to 5000 kbits/s. For upload = similarly 1200/970/500, all kbits/s. >=20 > I can now mostly watch video in iPlayer and download at circa 300 - = 400 kbits/s simultaneously, using htb, with tc-stab disabled. >=20 > QED >=20 >=20 > On 25 Aug 2013, at 19:41, Dave Taht wrote: >=20 >> So it sounds like you need a lower setting for the download than what = you are using? It's not the upload that is your problem.=20 >>=20 >> Netanalyzer sends one packet stream and thus measures 1 queue only. = fq_codel will happily give it one big queue for a while, while still = interleaving other flows's packets into the stream at every opportunity.=20= >>=20 >> as for parsing rrul I generally draw a line with my hand and multiply = by 4, then fudge in the numbers for the reverse ack and measurement = streams.=20 >=20 > You are saying that you judge the result solely by eye. presumably. >=20 >>=20 >> As written it was targetted at 4Mbit and up which is why the samples = are discontinuous in your much lower bandwidth situation.=20 >=20 > Aha. Problem solved. >=20 >>=20 >> I do agree that rrul could use a simpler implementation, perhaps one = that tested two download streams only, and provided an estimate as to = the actual bandwidth usage, and scale below 4Mbit better. >>=20 >>=20 >> On Sun, Aug 25, 2013 at 11:30 AM, Fred Stratton = wrote: >>=20 >> On 25 Aug 2013, at 18:53, Sebastian Moeller wrote: >>=20 >> > Hi Fred, >> > >> > >> > On Aug 25, 2013, at 16:26 , Fred Stratton = wrote: >> > >> >> Thank you. >> >> >> >> This is an initial response. >> >> >> >> Am using 3.10.2-1 currently, with the standard AQM interface. This = does not have the pull down menu of your interface, which is why I ask = if both are active. >> > >> > I have seen your follow-up mail that you actually used = 3.10.9-2. I think that has the first cut of the script modifications = that still allow to select both. Since I have not tested it any other = way I would recommend to enable just one of them at the same time. Since = the implementation of both is somewhat orthogonal and htb_private = actually works in 3.10.9, best case you might actually get the link = layer adjustments (LLA) and the overhead applied twice, wasting = bandwidth. So please either use the last set of modified files I send = around or wait for Dave to include them in ceropackages=85 >>=20 >> I have retained the unmodified script. I shall return to that. >>=20 >>=20 >> > >> >> On 25 Aug 2013, at 14:59, Sebastian Moeller = wrote: >> >> >> >>> Hi Fred, >> >>> >> >>> >> >>> On Aug 25, 2013, at 12:17 , Fred Stratton = wrote: >> >>> >> >>>> >> >>>> On 25 Aug 2013, at 10:21, Fred Stratton = wrote: >> >>>> >> >>>>> As the person with the most flaky ADSL link, I point out that = None of these recent, welcome, changes, are having any effect here, with = an uplink sped of circa 950 kbits/s. >> >>> >> >>> Okay, how flaky is you link? What rate of Errors do you have = while testing? I am especially interested in CRC errors and ES SES and = HEC, just to get an idea how flaky the line is... >> >>> >> >>>>> >> >>>>> The reason I mention this is that it is still impossible to = watch iPlayer Flash streaming video and download at the same time, The = iPlayer stream fails. The point of the exercise was to achieve this. >> >>>>> >> >>>>> The uplink delay is consistently around 650ms, which appears to = be too high for effective streaming. In addition, the uplink stream has = multiple breaks, presumably outages, if the uplink rate is capped at, = say, 700 kbits/s. >> >>> >> >>> Well, watching video is going to stress your downlink so the = uplink should not saturate by the ACKs and the concurrent downloads also = do not stress your uplink except for the ACKs, so this points to = downlink errors as far as I can tell from the data you have given. If = the up link has repeated outages however, your problems might be = unfixable because these, if long enough, will cause lost ACKs and will = probably trigger retransmission, independent of whether the link layer = adjustments work or not. (You could test this by shaping you up and = downlink to <=3D 50% of the link rates and disable all link layer = adjustments, 50% is larger than the ATM worst case so should have you = covered. Well unless you del link has an excessive number of tones = reserved for forward error correction (FEC)). >> >> >> >> Uptime 100655 >> >> downstream 12162 kbits/s >> >> CRC errors 10154 >> >> FEC Errors 464 >> >> hEC Errors 758 >> >> >> >> upstream 1122 kbits/s >> >> no errors in period. >> > >> > Ah, I think you told me in the past that "Target snr upped to = 12 deciBel. Line can sustain 10 megabits/s with repeated loss of = sync.at lower snr. " so sync at 12162 might be too aggressive, no? But = the point is that as I understand iPlayer works fine without competing = download traffic? To my eye the error numbers look small enough to not = be concerned about. Do you know how long the error correction period is? >>=20 >> The correction period is probably circa 28 hours. Have moved to using = the HG612. This is uses the Broadcom 6368 SoC. Like most of the devices = I use, it fell out of a BT van and on to ebay. It is the standard device = used for connecting FTTC installations in the UK. With a simple = modification, it will work stably with ADSL2+. >>=20 >> Ihe sync rate has gone up considerably, not because I have changed = the Target SNR from 12 Decibel, but because I am now using a Broadcom = chipset and software blob with a DSLAM which returns BDCM when = interrogated. >> > >> > >> >> >> >>> Could you perform the following test by any chance: state = iPlayer and yor typical downloads and then have a look at = http://gw.home.lan:81und the following tab chain Status -> Realtime = Graphs -> Traffic -> Realtime Traffic. If during your test the Outbound = rate stays well below you shaped limit and you still encounter the = stream failure I would say it is save to ignore the link layer = adjustments as cause of your issues. >> >> >> >> Am happy reducing rate to fifty per cent, but the uplink appears = to have difficulty operating below circa 500 kbits/s. This should not be = so. I shall try a fourth time. >> > >> > That sounds weird, if you shape to below 500 upload stops = working or just gets choppier? Looking at your sync data 561 would fit = the ~50% and above 500 requirements. >>=20 >> I was basing the judgment on Netalyzr data. DT and you now say this = is suspect. However, netsurf-wrapper traces are discontinuous. The = actual real time trace looks perfectly normal. >>=20 >> iPlayer is a Flash based player which is web page embedded. The ipv4 = user address is parsed to see if it is in the UK. It plays BBC TV = programs. It most likely is badly designed and written. It is the way I = watch TV. Like all UK residents, I pay the bloated bureaucracy of the = BBC a yearly fee of about 200 euro. If I do not pay, I will be fined. = You will be surprised that I am not a fan of the BBC. iPlayer starts and = runs fine, but if a download is commenced whilst it is running, so I can = watch the propaganda put out as national news, the video will stall and = the continue, but most commonly will stop. >> > >> > >> >>> >> >>> >> >>>>> >> >>>>> YouTube has no problems. >> >>>>> >> >>>>> I remain unclear whether the use of tc-stab and htb are = mutually exclusive options, using the present stock interface. >> >>> >> >>> Well, depending on the version of the cerowrt you use, = <3.10.9-1 I believe lacks a functional HTB link layer adjustment = mechanism, so you should select tc_stab. My most recent modifications to = Toke and Dave's AQM package does only allow you to select one or the = other. In any case selecting BOTH is not a reasonable thing to do, = because best case it will only apply overhead twice, worst case it would = also do the (link layer adjustments) LLA twice >> >> >> >> >> >>> See initial comments. >> >>> >> >>>>> >> >>>>> The current ISP connection is IPoA LLC. >> >>>> >> >>>> Correction - Bridged LLC. >> >>> >> >>> Well, I think you should try to figure out your overhead = empirically and check the encapsulation. I would recommend you run the = following script on you r link over night and send me the log file it = produces: >> >>> >> >>> #! /bin/bash >> >>> # TODO use seq or bash to generate a list of the requested sizes = (to alow for non-equdistantly spaced sizes) >> >>> >> >>> # Telekom Tuebingen Moltkestrasse 6 >> >>> TECH=3DADSL2 >> >>> # finding a proper target IP is somewhat of an art, just = traceroute a remote site >> >>> # and find the nearest host reliably responding to pings showing = the smallet variation of pingtimes >> >>> TARGET=3D87.186.197.70 # T >> >>> DATESTR=3D`date +%Y%m%d_%H%M%S` # to allow multiple = sequential records >> >>> LOG=3Dping_sweep_${TECH}_${DATESTR}.txt >> >>> >> >>> >> >>> # by default non-root ping will only end one packet per second, = so work around that by calling ping independently for each package >> >>> # empirically figure out the shortest period still giving the = standard ping time (to avoid being slow-pathed by our host) >> >>> PINGPERIOD=3D0.01 # in seconds >> >>> PINGSPERSIZE=3D10000 >> >>> >> >>> # Start, needed to find the per packet overhead dependent on the = ATM encapsulation >> >>> # to reliably show ATM quantization one would like to see at = least two steps, so cover a range > 2 ATM cells (so > 96 bytes) >> >>> SWEEPMINSIZE=3D16 # 64bit systems seem to require 16 = bytes of payload to include a timestamp... >> >>> SWEEPMAXSIZE=3D116 >> >>> >> >>> >> >>> n_SWEEPS=3D`expr ${SWEEPMAXSIZE} - ${SWEEPMINSIZE}` >> >>> >> >>> >> >>> i_sweep=3D0 >> >>> i_size=3D0 >> >>> >> >>> while [ ${i_sweep} -lt ${PINGSPERSIZE} ] >> >>> do >> >>> (( i_sweep++ )) >> >>> echo "Current iteration: ${i_sweep}" >> >>> # now loop from sweepmin to sweepmax >> >>> i_size=3D${SWEEPMINSIZE} >> >>> while [ ${i_size} -le ${SWEEPMAXSIZE} ] >> >>> do >> >>> echo "${i_sweep}. repetition of ping size ${i_size}" >> >>> ping -c 1 -s ${i_size} ${TARGET} >> ${LOG} & >> >>> (( i_size++ )) >> >>> # we need a sleep binary that allows non integer times (GNU = sleep is fine as is sleep of macosx 10.8.4) >> >>> sleep ${PINGPERIOD} >> >>> done >> >>> done >> >>> >> >>> #tail -f ${LOG} >> >>> >> >>> echo "Done... ($0)" >> >>> >> >>> >> >>> Please set TARGET to the closest IP host on the ISP side of your = link that gives reliable ping RTTs (using "ping -c 100 -s 16 = your.best.host.ip"). Also test whether the RTTs are in the same ballpark = when you reduce the ping period to 0.01 (you might have to increase the = period until the RTTs are close to the standard 1 ping per second case). = I can then run this through my matlab code to detect the actual = overhead. (I am happy to share the code as well, if you have matlab = available; it might even run under octave but I have not tested that = since the last major changes). >> >> >> >> To follow at some point. >> > >> > Oh, I failed to mention at the given parameters the script = takes almost 3 hours, during which the link should be otherwise idle... >> > >> >>> >> >>> >> >>>> >> >>>>> Whatever byte value is used for tc-stab makes no change. >> >>> >> >>> I assume you talk about the overhead? Missing link layer = adjustment will eat between 50% and 10% of your link bandwidth, while = missing overhead values will be more benign. The only advise I can give = is to pick the overhead that actually describes your link. I am willing = to help you figure this out. >> >> >> >> The link is bridged LLC. Have been using 18 and 32 for test = purposes. I shall move to PPPoA VC-MUX in 4 months. >> > >> > I guess figuring out you exact overhead empirically is going = to be fun. >> > >> >>> >> >>>>> >> >>>>> I have applied the ingress modification to simple.qos, keeping = the original version., and tested both. >> >>> >> >>> For which cerowrt version? It is only expected to do = something for 3.10.9-1 and upwards, before that the HTB lionklayer = adjustment did NOT work. >> >> >> >> Using 3.10.9-2 >> > >> > Yeah as stated above, I would recommend to use either or, not = both. If you took RRUL data you might be able to compare the three = conditions. I would estimate the most interesting part would be in the = sustained ravager up and download rates here. >>=20 >> How do you obtain an average i.e. mean rate from the RRUL graph? >> > >> > >> >> >> >>> >> >>>>> >> >>>>> I have changed the Powerline adaptors I use to ones with known = smaller buffers, though this is unlikely to be a ate-limiting step. >> >>>>> >> >>>>> I have changed the 2Wire gateway, known to be heavily buffered, = with a bridged Huawei HG612, with a Broadcom 6368 SoC. >> >>>>> >> >>>>> This device has a permanently on telnet interface, with a = simple password, which cannot be changed other than by firmware = recompilation=85 >> >>>>> >> >>>>> Telnet, however, allows txqueuelen to be reduced from 1000 to = 0. >> >>>>> >> >>>>> None of these changes affect the problematic uplink delay. >> >>> >> >>> So how did you measure the uplink delay? The RRUL plots you = sent me show an increase in ping RTT from around 50ms to 80ms with = tc_stab and fq_codel on simplest.qos, how does that reconcile with 650ms = uplink delay, netalyzr? >> >> >> >> Max Planck and Netalyzr produce the same figure. I use both, but = Max Planck gives you circa 3 tries per IP address per 24 hours. >> > >> > Well, both use the same method which is not to meaningful if = you use fq_codel on a shaped link (unless you want to optimize your = system for UDP floods :) ) >> > >> > [snipp] >> > >> > >> > Best Regards >> > Sebastian >>=20 >> _______________________________________________ >> Cerowrt-devel mailing list >> Cerowrt-devel@lists.bufferbloat.net >> https://lists.bufferbloat.net/listinfo/cerowrt-devel >>=20 >>=20 >>=20 >> --=20 >> Dave T=E4ht >>=20 >> Fixing bufferbloat with cerowrt: = http://www.teklibre.com/cerowrt/subscribe.html >=20 >=20 > _______________________________________________ > Cerowrt-devel mailing list > Cerowrt-devel@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cerowrt-devel >=20 >=20 >=20 >=20 > --=20 > Dave T=E4ht >=20 > Fixing bufferbloat with cerowrt: = http://www.teklibre.com/cerowrt/subscribe.html > _______________________________________________ > Cerowrt-devel mailing list > Cerowrt-devel@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/cerowrt-devel