In 2021, engineers from Apple proposed an "RPM" (for revolutions per minute or rounds per minute) metric as a figure of merit related to responsiveness. Rather than using round-trip times, the metric counts (application-level) request/response times achievable over a fixed timescale. The idea is that consumers appreciate this because of the general experience that "higher is better".
An important point is that RPM should be measured while the Internet connection is in use. The authors propose to run several data transfers in parallel while measuring responsiveness.
Implementation
An implementation of the RPM metric is included in the networkQuality tool in macOS 10.15 and higher (and possibly in IOS, to be verified).
References
- draft-cpaasch-ippm-responsiveness-00 Responsiveness Under Working Conditions, Christoph Paasch, Randall Meyer, Stuart Cheshire, Omer Shapira, August 2021
- Reduce Network Delays For Your App, Stuart Cheshire, Christoph Paasch, WWDC 2021, video recording, June 2021
- rpm mailing list, bufferbloat.net, last accessed September 2021
- Toward a Consumer Responsiveness Metric, R. Brown, blog post, September 2021