[WIP] Added example of an executor that tracks the idle time.

[fakusb]

An example for the rp pico towards https://embassy.dev/book/dev/faq.html#_how_can_i_measure_resource_usage_cpu_ram_etc

1. Does anyone have comments on the example code itself?
2. If I'm not mistaken, the executor would treat time spend during an interrupt (e.g. all the tasks in an InterruptExecutor) as idle time, because the interrupt handler is executed before the non-interupt-level code after the wfe-instruction is executed. This kind of caveat should probably be made even more explicit?

[Dirbaio]

this is missing a *100

[Dirbaio]

If I'm not mistaken, the executor would treat time spend during an interrupt (e.g. all the tasks in an InterruptExecutor) as idle time, because the interrupt handler is executed before the non-interupt-level code after the wfe-instruction is executed. This kind of caveat should probably be made even more explicit?

there's a way around this: you can do the wfe inside a critical section. If an interrupt becomes pending, it still causes the wfe to exit, but the interrupt isn't handled yet because it's disabled. You can then count the elapsed time as idle then exit the critical section, so the interrupt time is not counted as idle.

[Dirbaio]

i'm marking as draft, please mask as ready to review when it's no longer WIP.