[Starlink] [Rpm] so great to see ISPs that care

rjmcmahon rjmcmahon at rjmcmahon.com
Sun Mar 12 17:02:31 EDT 2023 

iperf 2 uses responses per second and also provides the bounce back 
times as well as one way delays.

The hypothesis is that network engineers have to fix KPI issues, 
including latency, ahead of shipping products.

Asking companies to act on consumer complaints is way too late. It's 
also extremely costly. Those running Amazon customer service can explain 
how these consumer calls about their devices cause things like device 
returns (as that's all the call support can provide.) This wastes energy 
to physically ship things back, causes a stack of working items that now 
go to ewaste, etc.

It's really on network operators, suppliers and device mfgs to get ahead 
of this years before consumers get their stuff.

As a side note, many devices select their WiFi chanspec (AP channel+) 
based on the strongest RSSI. The network paths should be based on KPIs 
like low latency. Strong signal just means an AP is yelling to loudly 
and interfering with the neighbors. Try the optimal AP chanspec that has 
10dB separation per spatial dimension and the whole apartment complex 
would be better for it.

We're so focused on buffer bloat we're ignoring everything else where 
incremental engineering has led to poor products & offerings.

[rjmcmahon at ryzen3950 iperf2-code]$ iperf -c 192.168.1.72 -i 1 -e 
--bounceback --trip-times
------------------------------------------------------------
Client connecting to 192.168.1.72, TCP port 5001 with pid 3123814 (1 
flows)
Write buffer size:  100 Byte
Bursting:  100 Byte writes 10 times every 1.00 second(s)
Bounce-back test (size= 100 Byte) (server hold req=0 usecs & 
tcp_quickack)
TOS set to 0x0 and nodelay (Nagle off)
TCP window size: 16.0 KByte (default)
Event based writes (pending queue watermark at 16384 bytes)
------------------------------------------------------------
[  1] local 192.168.1.69%enp4s0 port 41336 connected with 192.168.1.72 
port 5001 (prefetch=16384) (bb w/quickack len/hold=100/0) (trip-times) 
(sock=3) (icwnd/mss/irtt=14/1448/284) (ct=0.33 ms) on 2023-03-12 
14:01:24.820 (PDT)
[ ID] Interval        Transfer    Bandwidth         BB 
cnt=avg/min/max/stdev         Rtry  Cwnd/RTT    RPS
[  1] 0.00-1.00 sec  1.95 KBytes  16.0 Kbits/sec    
10=0.311/0.209/0.755/0.159 ms    0   14K/202 us    3220 rps
[  1] 1.00-2.00 sec  1.95 KBytes  16.0 Kbits/sec    
10=0.254/0.180/0.335/0.051 ms    0   14K/210 us    3934 rps
[  1] 2.00-3.00 sec  1.95 KBytes  16.0 Kbits/sec    
10=0.266/0.168/0.468/0.088 ms    0   14K/210 us    3754 rps
[  1] 3.00-4.00 sec  1.95 KBytes  16.0 Kbits/sec    
10=0.294/0.184/0.442/0.078 ms    0   14K/233 us    3396 rps
[  1] 4.00-5.00 sec  1.95 KBytes  16.0 Kbits/sec    
10=0.263/0.150/0.427/0.077 ms    0   14K/215 us    3802 rps
[  1] 5.00-6.00 sec  1.95 KBytes  16.0 Kbits/sec    
10=0.325/0.237/0.409/0.056 ms    0   14K/258 us    3077 rps
[  1] 6.00-7.00 sec  1.95 KBytes  16.0 Kbits/sec    
10=0.259/0.165/0.410/0.077 ms    0   14K/219 us    3857 rps
[  1] 7.00-8.00 sec  1.95 KBytes  16.0 Kbits/sec    
10=0.277/0.193/0.415/0.068 ms    0   14K/224 us    3608 rps
[  1] 8.00-9.00 sec  1.95 KBytes  16.0 Kbits/sec    
10=0.292/0.206/0.465/0.072 ms    0   14K/231 us    3420 rps
[  1] 9.00-10.00 sec  1.95 KBytes  16.0 Kbits/sec    
10=0.256/0.157/0.439/0.082 ms    0   14K/211 us    3908 rps
[  1] 0.00-10.01 sec  19.5 KBytes  16.0 Kbits/sec    
100=0.280/0.150/0.755/0.085 ms    0   14K/1033 us    3573 rps
[  1] 0.00-10.01 sec  OWD Delays (ms) Cnt=100 To=0.169/0.074/0.318/0.056 
 From=0.105/0.055/0.162/0.024 Asymmetry=0.065/0.000/0.172/0.049    3573 
rps
[  1] 0.00-10.01 sec BB8(f)-PDF: 
bin(w=100us):cnt(100)=2:14,3:57,4:20,5:8,8:1 
(5.00/95.00/99.7%=2/5/8,Outliers=0,obl/obu=0/0)


Bob
> Dave,
> 
> your presentation was awesome, I fully agree with you ;). I very much
> liked your practical funnel demonstration which was boiled down to the
> bare minimum (I only partly asked myself, will the liquid spill in in
> your laptops keyboard, and if so is it water-proof, but you clearly
> had rehearsed/tried that before).
> BTW, I always have to think of this
> h++ps://www.youtube.com/watch?v=R7yfISlGLNU somehow when you present
> live from the marina ;)
> 
> 
> I am still not through watching all of the presentations and panels,
> but can already say, team L4S continues to over-promise and
> under-deliver, but Koen's presentation itself was done well and might
> (sadly) convince people to buy-in into L4(S) = 2L2L = too little, too
> late.
> 
> Stuart's RPM presentation was great, making a convincing point.
> (Except for pitching L4S and LLD as "solutions", I will accept them as
> a step in the right direction, but why not go in all the way and
> embrace proper scheduling?)
> 
> In detail though, I am not fully convinced about the decision of
> taking the inverse of delay increase as singular measure here as I
> consider that as a bit of a squandered opportunity at public
> outreach/education and as comparing idle and working RPM is
> non-intuitive, while idle and working RTT can immediately subtracted
> to see the extent of the queueing damage in actionable terms.
> 
> Try the same with RPM values:
> 
> 123-1234567:~ user$ networkQuality -v
> ==== SUMMARY ====
> 
> Upload capacity: 22.208 Mbps
> Download capacity: 88.054 Mbps
> Upload flows: 12
> Download flows: 12
> Responsiveness: High (2622 RPM)
> Base RTT: 18
> Start: 3/12/23, 21:00:58
> End: 3/12/23, 21:01:08
> OS Version: Version 12.6.3 (Build 21G419)
> 
> here we can divide 60 [sec/minute] * 1000 [ms/sec] by the RPM [1/min]
> to get: 60000/2622 = 22.88 ms loaded delay and subtract the base RTT
> of 18 for 60000/2622 - 18 = 4.88 ~5ms of loaded delay which is a
> useful quantity when managing a delay budget (this test was performed
> over wired ethernet with competent AQM and traffic shaping on the
> link, so no surprise about the outcome there). Let's look at the
> reverse and convert the base RTT into a base RPM score instead:
> 6000/18 = 333 rpm, what exactly does the delta RPM of 2622-333 =
> 2289rpm now tell us about the difference between idle and working
> conditions? [Well, since conversion is not witchcraft, I will be fine
> as will other interested in actual evoked delay, but we could have
> gotten a better measure*]
> 
> And all for the somewhat unhelpful car analogy... (it is not that for
> internal combustion engines bigger is necessarily better for RPM,
> either for torque or fuel efficiency).
> 
> I guess that ship has sailed though and RPM it is
> 
> *) Stuart notes that milliseconds and Hertz sound to sciency, but they
> could simply have given the delay increase in milliseconds a fancier
> name to solve that specific problem...
> 
> 
>> On Mar 12, 2023, at 20:31, Dave Taht via Rpm 
>> <rpm at lists.bufferbloat.net> wrote:
>> 
>> https://www.reddit.com/r/HomeNetworking/comments/11pmc9a/comment/jbypj0z/?context=3
>> 
>> --
>> Come Heckle Mar 6-9 at: https://www.understandinglatency.com/
>> Dave Täht CEO, TekLibre, LLC
>> _______________________________________________
>> Rpm mailing list
>> Rpm at lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/rpm
> 
> _______________________________________________
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