Is there a way to use this to get overall system usage over all processes?

[replaysMike]

I'm not sure if you've already got something for this, but it doesn't look possible unless GetByProcess() could take in a process, and not just assume the current process.

[replaysMike]

still digesting most of the code, but looks to be a limitation of getrusage that doesn't expose a way to do it by process id.

[devizer]

I'm not sure if you've already got something for this, but it doesn't look possible unless GetByProcess() could take in a process, and not just assume the current process.

Why not System.Diagnostics.Process' properties:
https://learn.microsoft.com/ru-ru/dotnet/api/system.diagnostics.process.userprocessortime
https://learn.microsoft.com/ru-ru/dotnet/api/system.diagnostics.process.totalprocessortime

[devizer]

still digesting most of the code, but looks to be a limitation of getrusage that doesn't expose a way to do it by process id.

getrusage is Linux implementation.
For Linux please take a look at https://github.com/devizer/Universe.NativeLinux.Interop, https://www.nuget.org/packages/Universe.LinuxTaskStats
The metrics include CPU Usage, counters and delays caused by IO, swap-in, memory reclaim, and memory trashing.

[replaysMike]

I ended up getting everything working surprisingly well using GetSystemTimes (Win32) for the Windows side, and System.Diagnostics.Process on Linux side. They both ended up mimicking the same output as Task manager (or very, very close). Your code helped me get through figuring it out - I haven't tested MacOS yet though. Nice repo!