The CPU_USAGE diagnostic frequently reports NaN on Mac OS

[inodentry]

Bevy version

Bevy 0.13

Relevant system information

SystemInfo { os: "MacOS 14.3.1 ", kernel: "23.3.0", cpu: "Apple M1 Pro", core_count: "10", memory: "32.0 GiB" }

What you did

Read the value of the SystemInformationDiagnosticsPlugin::CPU_USAGE diagnostic.

What went wrong

If I read the latest value(), it occasionally returns NaN. There are often sane values on most frame updates, but they are interspersed with lots of frequent NaNs.

If I read the smoothed() value, it shows NaN all the time. (due to presence of NaNs amongst measured values)

Additional information

This issue is Mac OS specific. On Linux and Windows, there are no NaNs and the values are always sane.

[alice-i-cecile]

We should omit NaN values when computing smoothed diagnostics. However we should also report the NaNs upstream to sysinfo: I checked https://github.com/GuillaumeGomez/sysinfo/issues?q=is%3Aissue+is%3Aopen+macos and could not find a prior report.

[Brezak]

Do we want to store NaNs at all?

[alice-i-cecile]

Storing these is useful information for the developer: if something goes wrong, I'd rather have "we couldn't get this data" in my logs, rather than a mysterious gap. We just need to be robust to them in our methods.