[Rpm] Changes to RPM calculation for MacOS Ventura?

[Sebastian Moeller]

Hi Christoph,

On 1 November 2022 22:52:21 CET, Christoph Paasch via Rpm <rpm at lists.bufferbloat.net> wrote:
>Hello Jonathan,
>
>> On Oct 28, 2022, at 2:45 PM, jf--- via Rpm <rpm at lists.bufferbloat.net> wrote:
>> 
>> Hopefully, Christoph can provide some details on the changes from the prior networkQuality test, as we’re seeing some pretty large changes in results for the latest RPM tests.
>> 
>> Where before we’d see results in the >1,500 RPM (and multiple >2,000 RPM results) for a DOCSIS 3.1 line with QoS enabled (180 down/35 up), it now returns peak download RPM of ~600 and ~800 for upload.
>> 
>> latest results:
>> 
>> ==== SUMMARY ====
>> Uplink capacity: 25.480 Mbps (Accuracy: High)
>> Downlink capacity: 137.768 Mbps (Accuracy: High)
>> Uplink Responsiveness: Medium (385 RPM) (Accuracy: High)
>> Downlink Responsiveness: Medium (376 RPM) (Accuracy: High)
>> Idle Latency: 43.875 milli-seconds (Accuracy: High)
>> Interface: en8
>> Uplink bytes transferred: 35.015 MB
>> Downlink bytes transferred: 154.649 MB
>> Uplink Flow count: 16
>> Downlink Flow count: 12
>> Start: 10/28/22, 5:12:30 PM
>> End: 10/28/22, 5:12:54 PM
>> OS Version: Version 13.0 (Build 22A380)
>> 
>> Latencies (as monitored via PingPlotter) stay absolutely steady during these tests,
>> 
>> So unless my ISP coincidentally started having major service issues, I’m scratching my head as to why.
>> 
>> For contrast, the Ookla result is as follows: https://www.speedtest.net/result/13865976456  with 15ms down, 18ms up loaded latencies.
>
>In Ventura, we started adding the latency on the load-generating connections to the final RPM-calulcation as well. The formula being used is now exactly what is in the v01 IETF draft.

[SM] I have been wondering quietly before whether reporting both inter- and intra-load-bearing flow responsiveness would not be a cool option for verbose mode? Both IMHO are giving relevant information about a link's usability under working conditions.

Regards
        Sebastian


>
>Very likely the bottleneck in your network does FQ, and so latency on separate connections is very low, while your load-generating connections are still bufferbloated.
>
>
>Ookla measures latency only on separate connections, thus will also be heavily impacted by FQ.
>
>
>Does that clarify it?
>
>
>Cheers,
>Christoph 
>
>
>> 
>> Further machine details: MacBook Pro 16” (2019) using a USB-C to Ethernet adapter.
>> I run with full ECN enabled:
>> sudo sysctl -w net.inet.tcp.disable_tcp_heuristics=1 
>> 
>> sudo sysctl -w net.inet.tcp.ecn_initiate_out=1
>> 
>> sudo sysctl -w net.inet.tcp.ecn_negotiate_in=1
>> 
>> and also with instant ack replies:
>> 
>> sysctl net.inet.tcp.delayed_ack
>> net.inet.tcp.delayed_ack: 0
>> 
>> I did try with delayed_ack=1, and the results were about the same.
>> 
>> Thanks in advance,
>> 
>> Jonathan Foulkes
>> 
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>

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