Remove cpu_relax from stabilized callback

[atneya]

cpu_relax may have unintended side effects leading to increased preemptions

[philburk]

What are the unintended side effects? What do you suggest as an alternative?

[philburk]

no-inline can be used to make a function that will always get called. Maybe do shifts and XOR on an input parameter that will get passed as zero. That might minimize gate flipping and reduce power.

[dturner]

A guy from Ableton (Ryan Brown?) gave a talk about how CPU frequency scaling was affecting iOS devices at ADC'19. He referenced the wfe instruction as a way of generating artificial load. Code here.

[philburk]

We are going to deprecate stabilized callback.