[Starlink] Optimized for Speedtest?
Nathan Owens
nathan at nathan.io
Wed Mar 16 09:40:58 EDT 2022
If you just UDP iperf the crap out of it, the bandwidth available is pretty
good:
[ ID] Interval Transfer Bitrate Jitter Lost/Total
Datagrams
[ 5] 0.00-1.00 sec 25.7 MBytes 216 Mbits/sec 0.026 ms 10078/28719
(35%)
[ 5] 1.00-2.00 sec 36.0 MBytes 302 Mbits/sec 0.031 ms 4178/30262
(14%)
[ 5] 2.00-3.00 sec 39.0 MBytes 327 Mbits/sec 0.053 ms 1961/30231
(6.5%)
[ 5] 3.00-4.00 sec 38.9 MBytes 326 Mbits/sec 0.059 ms 1787/29937
(6%)
[ 5] 4.00-5.00 sec 39.1 MBytes 328 Mbits/sec 0.026 ms 2166/30447
(7.1%)
[ 5] 5.00-6.00 sec 34.4 MBytes 289 Mbits/sec 0.030 ms 5274/30180
(17%)
[ 5] 6.00-7.00 sec 34.9 MBytes 293 Mbits/sec 0.066 ms 4982/30286
(16%)
[ 5] 7.00-8.00 sec 37.6 MBytes 316 Mbits/sec 0.136 ms 2915/30158
(9.7%)
[ 5] 8.00-9.00 sec 39.0 MBytes 327 Mbits/sec 0.040 ms 2004/30250
(6.6%)
[ 5] 9.00-10.00 sec 39.0 MBytes 327 Mbits/sec 0.055 ms 1977/30240
(6.5%)
[ 5] 10.00-11.00 sec 38.2 MBytes 320 Mbits/sec 0.029 ms 2539/30203
(8.4%)
[ 5] 11.00-12.00 sec 35.7 MBytes 299 Mbits/sec 0.070 ms 4349/30177
(14%)
[ 5] 12.00-13.00 sec 32.9 MBytes 276 Mbits/sec 0.028 ms 6336/30169
(21%)
[ 5] 13.00-14.00 sec 36.1 MBytes 303 Mbits/sec 0.027 ms 4110/30271
(14%)
[ 5] 14.00-15.00 sec 22.2 MBytes 186 Mbits/sec 0.033 ms 14245/30298
(47%)
[ 5] 15.00-16.00 sec 27.1 MBytes 227 Mbits/sec 0.066 ms 10529/30164
(35%)
[ 5] 16.00-17.00 sec 33.4 MBytes 280 Mbits/sec 0.057 ms 5989/30184
(20%)
[ 5] 17.00-18.00 sec 33.7 MBytes 283 Mbits/sec 0.046 ms 5804/30220
(19%)
[ 5] 18.00-19.00 sec 24.7 MBytes 207 Mbits/sec 0.032 ms 12323/30198
(41%)
[ 5] 19.00-20.00 sec 30.6 MBytes 257 Mbits/sec 0.044 ms 8129/30292
(27%)
[ 5] 20.00-21.00 sec 27.9 MBytes 234 Mbits/sec 0.030 ms 9905/30140
(33%)
[ 5] 21.00-22.00 sec 19.5 MBytes 164 Mbits/sec 0.059 ms 16089/30220
(53%)
[ 5] 22.00-23.00 sec 19.4 MBytes 163 Mbits/sec 0.069 ms 16147/30211
(53%)
[ 5] 23.00-24.00 sec 20.5 MBytes 172 Mbits/sec 0.035 ms 15355/30234
(51%)
[ 5] 24.00-25.00 sec 25.6 MBytes 215 Mbits/sec 0.030 ms 11634/30187
(39%)
[ 5] 25.00-26.00 sec 34.1 MBytes 286 Mbits/sec 0.061 ms 5681/30346
(19%)
[ 5] 26.00-27.00 sec 29.4 MBytes 247 Mbits/sec 0.037 ms 8787/30081
(29%)
[ 5] 27.00-28.00 sec 23.3 MBytes 196 Mbits/sec 0.056 ms 13361/30257
(44%)
[ 5] 28.00-29.00 sec 31.0 MBytes 260 Mbits/sec 0.028 ms 7750/30206
(26%)
[ 5] 29.00-30.00 sec 20.4 MBytes 171 Mbits/sec 0.033 ms 15422/30186
(51%)
[ 5] 30.00-31.00 sec 30.9 MBytes 259 Mbits/sec 0.039 ms 7761/30110
(26%)
[ 5] 31.00-32.00 sec 31.4 MBytes 263 Mbits/sec 0.055 ms 7641/30357
(25%)
[ 5] 32.00-33.00 sec 31.9 MBytes 268 Mbits/sec 0.062 ms 7069/30180
(23%)
[ 5] 33.00-34.00 sec 29.8 MBytes 250 Mbits/sec 0.028 ms 8630/30206
(29%)
[ 5] 34.00-35.00 sec 32.7 MBytes 274 Mbits/sec 0.056 ms 6638/30283
(22%)
[ 5] 35.00-36.00 sec 29.5 MBytes 247 Mbits/sec 0.066 ms 8800/30129
(29%)
[ 5] 36.00-37.00 sec 25.9 MBytes 217 Mbits/sec 0.038 ms 11501/30247
(38%)
[ 5] 37.00-38.00 sec 26.2 MBytes 220 Mbits/sec 0.050 ms 10978/29969
(37%)
[ 5] 38.00-39.00 sec 28.0 MBytes 235 Mbits/sec 0.038 ms 10208/30490
(33%)
[ 5] 39.00-40.00 sec 25.2 MBytes 211 Mbits/sec 0.109 ms 11942/30171
(40%)
[ 5] 40.00-41.00 sec 24.7 MBytes 208 Mbits/sec 0.022 ms 12360/30279
(41%)
[ 5] 41.00-42.00 sec 24.1 MBytes 202 Mbits/sec 0.041 ms 12587/30040
(42%)
[ 5] 42.00-43.00 sec 26.0 MBytes 218 Mbits/sec 0.032 ms 11635/30444
(38%)
[ 5] 43.00-44.00 sec 26.0 MBytes 218 Mbits/sec 0.063 ms 11318/30153
(38%)
[ 5] 44.00-45.00 sec 23.3 MBytes 196 Mbits/sec 0.028 ms 13279/30183
(44%)
[ 5] 45.00-46.00 sec 34.8 MBytes 292 Mbits/sec 0.046 ms 5008/30227
(17%)
[ 5] 46.00-47.00 sec 35.2 MBytes 295 Mbits/sec 0.041 ms 4838/30334
(16%)
[ 5] 47.00-48.00 sec 29.1 MBytes 244 Mbits/sec 0.068 ms 9052/30147
(30%)
[ 5] 48.00-49.00 sec 26.0 MBytes 218 Mbits/sec 0.040 ms 11421/30222
(38%)
[ 5] 49.00-50.00 sec 25.4 MBytes 213 Mbits/sec 0.049 ms 11798/30207
(39%)
[ 5] 50.00-51.00 sec 27.3 MBytes 229 Mbits/sec 0.057 ms 10412/30217
(34%)
[ 5] 51.00-52.00 sec 24.9 MBytes 209 Mbits/sec 0.030 ms 12179/30233
(40%)
[ 5] 52.00-53.00 sec 26.5 MBytes 222 Mbits/sec 0.045 ms 11067/30259
(37%)
[ 5] 53.00-54.00 sec 26.5 MBytes 223 Mbits/sec 0.025 ms 10985/30200
(36%)
[ 5] 54.00-55.00 sec 25.3 MBytes 212 Mbits/sec 0.099 ms 11861/30192
(39%)
[ 5] 55.00-56.00 sec 29.7 MBytes 249 Mbits/sec 0.034 ms 8714/30235
(29%)
[ 5] 56.00-57.00 sec 36.1 MBytes 303 Mbits/sec 0.053 ms 4051/30224
(13%)
[ 5] 57.00-58.00 sec 29.8 MBytes 250 Mbits/sec 0.048 ms 8622/30187
(29%)
[ 5] 58.00-59.00 sec 31.6 MBytes 265 Mbits/sec 0.029 ms 7481/30353
(25%)
[ 5] 59.00-60.00 sec 14.2 MBytes 119 Mbits/sec 0.040 ms 19884/30175
(66%)
[ 5] 60.00-61.00 sec 33.3 MBytes 279 Mbits/sec 0.034 ms 6223/30336
(21%)
[ 5] 61.00-62.00 sec 32.7 MBytes 274 Mbits/sec 0.034 ms 6490/30157
(22%)
[ 5] 62.00-63.00 sec 33.3 MBytes 279 Mbits/sec 0.034 ms 6099/30217
(20%)
[ 5] 63.00-64.00 sec 31.4 MBytes 264 Mbits/sec 0.024 ms 7409/30162
(25%)
[ 5] 64.00-65.00 sec 34.3 MBytes 288 Mbits/sec 0.031 ms 5504/30328
(18%)
[ 5] 65.00-66.00 sec 34.4 MBytes 288 Mbits/sec 0.077 ms 5316/30216
(18%)
[ 5] 66.00-67.00 sec 34.2 MBytes 287 Mbits/sec 0.042 ms 5424/30167
(18%)
[ 5] 67.00-68.00 sec 29.4 MBytes 247 Mbits/sec 0.034 ms 8900/30223
(29%)
[ 5] 68.00-69.00 sec 33.4 MBytes 280 Mbits/sec 0.050 ms 6052/30203
(20%)
[ 5] 69.00-70.00 sec 34.4 MBytes 289 Mbits/sec 0.031 ms 5312/30259
(18%)
[ 5] 70.00-71.00 sec 34.4 MBytes 288 Mbits/sec 0.049 ms 5308/30198
(18%)
[ 5] 71.00-72.00 sec 30.8 MBytes 259 Mbits/sec 0.031 ms 7835/30169
(26%)
[ 5] 72.00-73.00 sec 33.9 MBytes 284 Mbits/sec 0.063 ms 5730/30254
(19%)
[ 5] 73.00-74.00 sec 33.4 MBytes 280 Mbits/sec 0.045 ms 6012/30226
(20%)
[ 5] 74.00-75.00 sec 20.0 MBytes 168 Mbits/sec 0.039 ms 15586/30062
(52%)
[ 5] 75.00-75.51 sec 10.2 MBytes 166 Mbits/sec 0.057 ms 8141/15495
(53%)
On Tue, Mar 15, 2022 at 3:47 PM Nathan Owens <nathan at nathan.io> wrote:
> Here’s what it looks like for a sustained download:
> https://i.redd.it/odo31ofu4t971.png
> This was from a while ago, most of those latency spikes have been
> dampened.
>
> On Tue, Mar 15, 2022 at 3:39 PM Dave Taht <dave.taht at gmail.com> wrote:
>
>> On Tue, Mar 15, 2022 at 5:09 PM Daniel AJ Sokolov <daniel at falco.ca>
>> wrote:
>> >
>> > Hello,
>> >
>> > From this list I have learned that Starlink is optimized to shine in
>> > tests with speedtest.net and similar sites, but that transmission rates
>> > drop quickly after about 15 seconds.
>>
>> That is not strictly true. The trend is a low rate for the initial
>> 15s, then a boost, then variable. It happens that speedtest reports
>> the *last* result in the typically 20s it runs,
>> so by that light is starlink is "optimized for speedtest". Much of the
>> internet is "optimized for speedtest", tons of services basically blow
>> up classic tcp congestion controls at T+21s.
>>
>> Attached are two example flent test runs, a rrul test from one project
>> member's dishy, and a tcp_nup test from anothers.
>>
>> For reference also attached is how a present day WISP 60Ghz radio
>> functions, one which has FQ and AQM, with consistent bandwidth, and
>> only ~5ms latency swings. Ideally the latency on starlink would not go
>> over 10ms their baseline ~40ms latency, under these loads.
>>
>> Comparing the later two tests you can see the inversions between
>> bandwidth and latency that come from the fixed length fifos starlink
>> uses at any of the roughly 3
>> speed settings we currently see.
>>
>> PS - most web pages cannot use more than 25MBit in the 3s they typically
>> take.
>>
>> > How do they do that, technically?
>>
>> Allocate bandwidth? Unknown. Ever 15s seems silly. Not modifying queue
>> length and/not using a smarter queuing algo like fq_codel or cake when
>> they do change the bandwidth allocation is the simple flaw in their
>> design I keep hoping they'll fix.
>>
>> >
>> > Is that a result of Bufferbloat?
>>
>> Yes. The rrul test is often illustrative of the problem on how slowly
>> the internet operates during an upload clogging up the queue, or vice
>> versa. Most ISPs do some sort of ack filtering or prioritization to
>> make uploads interfere less with downloads, or use AQM, fq or a
>> combination of both.
>>
>> > Is that a a specific code in the modem
>> > to cheat, like some car manufacturers cheated on emissions tests?
>>
>> I hope not. No, they do have limited capacity, do have to change sats,
>> do need to allocate bandwidth sanely. AND buffering.
>>
>> > Is
>> > that something done in the satellites who shift capacity from other
>> > users to those users who initiate downloads? Is that done on the
>> backhaul?
>>
>> Wish we knew. In my ideal world they would supply a statistic that a
>> sch_cake could take and vary the rate/buffering based on that on the
>> home router, or just do it more right
>> in the dishy and head ends with cake + BQL.
>>
>> >
>> > Thank you
>> > Daniel
>> > _______________________________________________
>> > Starlink mailing list
>> > Starlink at lists.bufferbloat.net
>> > https://lists.bufferbloat.net/listinfo/starlink
>>
>>
>>
>> --
>> I tried to build a better future, a few times:
>> https://wayforward.archive.org/?site=https%3A%2F%2Fwww.icei.org
>>
>> Dave Täht CEO, TekLibre, LLC
>> _______________________________________________
>> Starlink mailing list
>> Starlink at lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/starlink
>>
>
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