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@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
<r...@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
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