[Make-wifi-fast] D* tcp looks pretty good, on paper
Dave Taht
dave.taht at gmail.com
Thu Jan 7 16:41:42 EST 2021
This is through one of the last remaining cerowrt boxes in the world,
running fq_codel. tcp-davis takes about a 20% single stream throughput
hit vs bbr.
I note, that I don't care one whit about throughput anymore. I care
that nothing, NOTHING messes up my videoconference...
and thus the tcp-rtt stats attached for davis are pleasing.
On Thu, Jan 7, 2021 at 12:26 PM Bob McMahon <bob.mcmahon at broadcom.com> wrote:
>
> FYI, one can try this out using iperf 2.1 with --trip-times. This gives end/end delay at the application level. One can use --trip-times when clocks
> are sync'd to get the write to read latencies which are the latencies at the application level.
>
> Note: I set up a Raspberry Pi 4 with a GPS hat from ubutronics for solderless pulse per second. Then configured it as a PTP grandmaster. This cost me around $200.
>
> I also added support for a very crude --near-congestion option that paces the writes based upon the weight of the RTT. The tcp_info struct is sampled and available
> for other experiments though one would have to modify the source a bit. This current technique used by iperf 2.1 is designed for test networks only where all
> traffic is under script control. We've had too many people measuring bloat as latency. We really need separate measurements between the two phenomena,
> bloat vs latency, because they require different eng actions for a semiconductor supplier.
>
> Below are examples over a 10G link, first with no write pacing then with it. The server output, shown first, has the latency data (as well as the net power
> and little's law calculation.) (Note: use --histograms for to get full distributions.)
>
> No write pacing
>
> [rjmcmahon at localhost iperf2-code]$ src/iperf -s -i 1 -e
> ------------------------------------------------------------
> Server listening on TCP port 5001 with pid 24568
> Read buffer size: 128 KByte (Dist bin width=16.0 KByte)
> TCP window size: 85.3 KByte (default)
> ------------------------------------------------------------
> [ 1] local 192.168.1.10%enp2s0 port 5001 connected with 192.168.1.62 port 50056 (MSS=1448) (trip-times) (sock=4) (peer 2.1.0-rc) on 2021-01-07 12:11:04 (PST)
> [ ID] Interval Transfer Bandwidth Burst Latency avg/min/max/stdev (cnt/size) inP NetPwr Reads=Dist
> [ 1] 0.00-1.00 sec 1.09 GBytes 9.34 Gbits/sec 2.959/1.180/3.681/0.388 ms (8905/131072) 3.31 MByte 394522 18480=2459:2580:2475:2354:2203:2192:1974:2243
> [ 1] 1.00-2.00 sec 1.10 GBytes 9.41 Gbits/sec 2.993/2.302/3.703/0.359 ms (8978/131072) 3.36 MByte 393209 19482=2526:2850:3102:2622:2344:2297:1867:1874
> [ 1] 2.00-3.00 sec 1.10 GBytes 9.42 Gbits/sec 3.010/2.302/3.692/0.347 ms (8978/131085) 3.38 MByte 391047 19387=2563:2757:2928:2708:2432:2244:1829:1926
> [ 1] 3.00-4.00 sec 1.10 GBytes 9.41 Gbits/sec 3.009/2.301/3.668/0.348 ms (8979/131060) 3.38 MByte 391094 18821=2456:2585:2660:2545:2270:2239:1906:2160
> [ 1] 4.00-5.00 sec 1.10 GBytes 9.42 Gbits/sec 2.985/2.299/3.696/0.359 ms (8979/131070) 3.35 MByte 394295 19441=2509:2886:2959:2728:2336:2200:1971:1852
> [ 1] 5.00-6.00 sec 1.10 GBytes 9.41 Gbits/sec 2.977/2.258/3.671/0.363 ms (8978/131082) 3.34 MByte 395352 18509=2352:2602:2464:2380:2263:2142:2095:2211
> [ 1] 6.00-7.00 sec 1.10 GBytes 9.41 Gbits/sec 2.980/2.290/3.680/0.363 ms (8978/131072) 3.34 MByte 394873 18522=2407:2499:2565:2334:2213:2268:1999:2237
> [ 1] 7.00-8.00 sec 1.10 GBytes 9.42 Gbits/sec 2.980/2.253/3.702/0.362 ms (8979/131073) 3.35 MByte 394972 18615=2427:2592:2493:2460:2281:2057:2062:2243
> [ 1] 8.00-9.00 sec 1.10 GBytes 9.41 Gbits/sec 2.976/2.277/3.663/0.364 ms (8979/131065) 3.34 MByte 395443 18632=2338:2615:2647:2351:2192:2317:2063:2109
> [ 1] 9.00-10.00 sec 1.10 GBytes 9.41 Gbits/sec 2.976/2.293/3.690/0.366 ms (8978/131076) 3.34 MByte 395416 18428=2281:2622:2497:2275:2178:2253:2129:2193
> [ 1] 0.00-10.00 sec 11.0 GBytes 9.41 Gbits/sec 2.984/1.180/3.703/0.362 ms (89736/131072) 3.35 MByte 394014 188367=24320:26609:26793:24757:22712:22211:19916:21049
>
>
> [rjmcmahon at localhost iperf2-code]src/iperf -c 192.168.1.10 --trip-times -i 1 -e
> ------------------------------------------------------------
> Client connecting to 192.168.1.10, TCP port 5001 with pid 18961 (1 flows)
> Write buffer size: 131072 Byte
> TCP window size: 85.0 KByte (default)
> ------------------------------------------------------------
> [ 1] local 192.168.1.62%enp2s0 port 50056 connected with 192.168.1.10 port 5001 (MSS=1448) (trip-times) (sock=3) (ct=0.41 ms) on 2021-01-07 12:11:04 (PST)
> [ ID] Interval Transfer Bandwidth Write/Err Rtry Cwnd/RTT NetPwr
> [ 1] 0.00-1.00 sec 1.09 GBytes 9.37 Gbits/sec 8937/0 0 1508K/1099 us 1065750
> [ 1] 1.00-2.00 sec 1.10 GBytes 9.41 Gbits/sec 8975/0 0 1508K/1087 us 1082218
> [ 1] 2.00-3.00 sec 1.10 GBytes 9.41 Gbits/sec 8975/0 0 1508K/1081 us 1088225
> [ 1] 3.00-4.00 sec 1.10 GBytes 9.42 Gbits/sec 8984/0 0 1508K/1085 us 1085300
> [ 1] 4.00-5.00 sec 1.10 GBytes 9.42 Gbits/sec 8980/0 0 1508K/1105 us 1065182
> [ 1] 5.00-6.00 sec 1.10 GBytes 9.41 Gbits/sec 8975/0 0 1582K/1100 us 1069428
> [ 1] 6.00-7.00 sec 1.10 GBytes 9.42 Gbits/sec 8979/0 0 1582K/1121 us 1049862
> [ 1] 7.00-8.00 sec 1.10 GBytes 9.41 Gbits/sec 8976/0 0 1582K/1133 us 1038396
> [ 1] 8.00-9.00 sec 1.10 GBytes 9.41 Gbits/sec 8978/0 0 1582K/1115 us 1055394
> [ 1] 9.00-10.00 sec 1.10 GBytes 9.42 Gbits/sec 8986/0 0 1582K/1122 us 1049744
> [ 1] 0.00-10.00 sec 11.0 GBytes 9.41 Gbits/sec 89748/0 0 1582K/1122 us 1048294
>
>
> With write pacing
>
> [rjmcmahon at localhost iperf2-code]$ src/iperf -s -i 1 -e
> ------------------------------------------------------------
> Server listening on TCP port 5001 with pid 24702
> Read buffer size: 128 KByte (Dist bin width=16.0 KByte)
> TCP window size: 85.3 KByte (default)
> ------------------------------------------------------------
> [ 1] local 192.168.1.10%enp2s0 port 5001 connected with 192.168.1.62 port 50072 (MSS=1448) (trip-times) (sock=4) (peer 2.1.0-rc) on 2021-01-07 12:14:59 (PST)
> [ ID] Interval Transfer Bandwidth Burst Latency avg/min/max/stdev (cnt/size) inP NetPwr Reads=Dist
> [ 1] 0.00-1.00 sec 1.08 GBytes 9.31 Gbits/sec 0.401/0.193/2.682/0.168 ms (8876/131084) 456 KByte 2904347 19868=3296:2404:2508:2797:3559:1778:1551:1975
> [ 1] 1.00-2.00 sec 1.10 GBytes 9.41 Gbits/sec 0.400/0.219/0.627/0.053 ms (8971/131071) 460 KByte 2937822 19117=3069:2267:2307:2510:3029:1824:1683:2428
> [ 1] 2.00-3.00 sec 1.09 GBytes 9.39 Gbits/sec 0.374/0.193/0.541/0.055 ms (8958/131060) 428 KByte 3143030 18942=2846:2423:2304:2417:2927:1831:1856:2338
> [ 1] 3.00-4.00 sec 1.09 GBytes 9.39 Gbits/sec 0.385/0.190/0.664/0.070 ms (8952/131072) 441 KByte 3050401 19248=3041:2175:2343:2749:3320:1805:1526:2289
> [ 1] 4.00-5.00 sec 1.09 GBytes 9.40 Gbits/sec 0.380/0.197/0.546/0.057 ms (8965/131075) 436 KByte 3095915 19959=3321:2398:2551:2738:3500:1840:1532:2079
> [ 1] 5.00-6.00 sec 1.09 GBytes 9.39 Gbits/sec 0.369/0.198/0.536/0.051 ms (8956/131072) 423 KByte 3177431 21060=3627:2456:2886:3189:4246:1813:1190:1653
> [ 1] 6.00-7.00 sec 1.09 GBytes 9.39 Gbits/sec 0.380/0.202/0.562/0.054 ms (8959/131077) 436 KByte 3086914 19263=3044:2338:2424:2505:3155:1809:1636:2352
> [ 1] 7.00-8.00 sec 1.09 GBytes 9.40 Gbits/sec 0.376/0.198/0.541/0.053 ms (8965/131061) 432 KByte 3122495 19137=3079:2303:2340:2455:3017:1822:1683:2438
> [ 1] 8.00-9.00 sec 1.10 GBytes 9.41 Gbits/sec 0.381/0.208/0.576/0.054 ms (8974/131073) 438 KByte 3083767 19162=3050:2269:2392:2486:3019:1891:1667:2388
> [ 1] 9.00-10.00 sec 1.09 GBytes 9.40 Gbits/sec 0.371/0.194/0.582/0.057 ms (8964/131070) 425 KByte 3169244 19143=3006:2411:2303:2462:3067:1744:1760:2390
> [ 1] 0.00-10.00 sec 10.9 GBytes 9.39 Gbits/sec 0.382/0.190/2.682/0.076 ms (89544/131072) 437 KByte 3074913 194908=31380:23444:24362:26308:32839:18161:16084:22330
>
>
> [rjmcmahon at localhost iperf2-code]$ src/iperf -c 192.168.1.10 --near-congestion=0.05 --trip-times -i 1 -e
> ------------------------------------------------------------
> Client connecting to 192.168.1.10, TCP port 5001 with pid 19320 (1 flows)
> Write buffer size: 131072 Byte
> TCP near-congestion delay weight set to 0.0500
> TCP window size: 85.0 KByte (default)
> ------------------------------------------------------------
> [ 1] local 192.168.1.62%enp2s0 port 50072 connected with 192.168.1.10 port 5001 (MSS=1448) (trip-times) (sock=3) (ct=0.40 ms) on 2021-01-07 12:14:59 (PST)
> [ ID] Interval Transfer Bandwidth Write/Err Rtry Cwnd/RTT NetPwr
> [ 1] 0.00-1.00 sec 1.08 GBytes 9.31 Gbits/sec 8881/0 0 1135K/373 us 3120427
> [ 1] 1.00-2.00 sec 1.10 GBytes 9.41 Gbits/sec 8971/0 0 1135K/391 us 3007281
> [ 1] 2.00-3.00 sec 1.09 GBytes 9.39 Gbits/sec 8958/0 0 1135K/331 us 3547260
> [ 1] 3.00-4.00 sec 1.09 GBytes 9.39 Gbits/sec 8952/0 0 1135K/288 us 4074155
> [ 1] 4.00-5.00 sec 1.09 GBytes 9.40 Gbits/sec 8965/0 0 1135K/301 us 3903855
> [ 1] 5.00-6.00 sec 1.09 GBytes 9.39 Gbits/sec 8955/0 0 1135K/414 us 2835144
> [ 1] 6.00-7.00 sec 1.09 GBytes 9.40 Gbits/sec 8961/0 0 1135K/470 us 2499013
> [ 1] 7.00-8.00 sec 1.09 GBytes 9.40 Gbits/sec 8964/0 0 1135K/350 us 3356941
> [ 1] 8.00-9.00 sec 1.10 GBytes 9.41 Gbits/sec 8973/0 0 1135K/472 us 2491756
> [ 1] 9.00-10.00 sec 1.09 GBytes 9.40 Gbits/sec 8964/0 0 1135K/402 us 2922710
> [ 1] 0.00-10.00 sec 10.9 GBytes 9.39 Gbits/sec 89547/0 0 1135K/402 us 2919642
>
> Bob
>
>
> On Thu, Jan 7, 2021 at 11:22 AM Taran Lynn via Make-wifi-fast <make-wifi-fast at lists.bufferbloat.net> wrote:
>>
>> The source can be found at https://github.com/lambda-11235/tcp_davis .
>>
>> The code mentioned in the paper can be found under the tag "arxiv_2020". The current master branch has an additional stable mode that I was testing out.
>>
>>
>> On Thu, Jan 7, 2021 at 10:35 AM Dave Taht <dave.taht at gmail.com> wrote:
>>>
>>> See: https://arxiv.org/pdf/2012.14996.pdf
>>>
>>> Things I really like:
>>>
>>> * they used flent
>>> * Using "variance" as the principal signal. This is essentially one of
>>> the great unpublished and unanalyzed improvements on the minstrel
>>> algorithm as well
>>> * Conventional ecn response
>>> * outperforms bbr on variable links
>>>
>>> Only negative so far is I haven't found any published source to it. :(
>>>
>>> Otherwise a very promising start to a year.
>>>
>>> "The choice of feedback mechanism between delay and packet loss has
>>> long been a point of contention in TCP congestion control. This has
>>> partly been resolved, as it has become increasingly evident that delay
>>> based methods are needed to facilitate modern interactive web
>>> applications. However, what has not been resolved is what control
>>> should be used, with the two candidates being the congestion window
>>> and the pacing rate. BBR is a new delay based congestion control
>>> algorithm that uses a pacing rate as its primary control and the
>>> congestion window as a secondary control. We propose that a congestion
>>> window first algorithm might give more desirable performance
>>> characteristics in situations where latency must be minimized even at
>>> the expense of some loss in throughput. To evaluate this hypothesis we
>>> introduce a new congestion control algorithm called TCP D*, which is a
>>> congestion window first algorithm that adopts BBR's approach of
>>> maximizing delivery rate while minimizing latency. In this paper, we
>>> discuss the key features of this algorithm, discuss the differences
>>> and similarity to BBR, and present some preliminary results based on a
>>> real implementation."
>>>
>>>
>>>
>>>
>>> --
>>> "For a successful technology, reality must take precedence over public
>>> relations, for Mother Nature cannot be fooled" - Richard Feynman
>>>
>>> dave at taht.net <Dave Täht> CTO, TekLibre, LLC Tel: 1-831-435-0729
>>
>> _______________________________________________
>> Make-wifi-fast mailing list
>> Make-wifi-fast at lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/make-wifi-fast
>
>
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dave at taht.net <Dave Täht> CTO, TekLibre, LLC Tel: 1-831-435-0729
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