Module Core_profiler.Common

now, possibly with calibration error.

slow_tasks is a list of functions that should be called rougly every second while the library is in use. The time-since-we-last-did-slow-tasks is checked on every call to now and maybe_do_slow_tasks below. add_slow_task adds one more slow task.

reluctance is higher if we don't want to do 'slow tasks' / don't want a potential 300ns spike.

We _really_ don't want this in Group.Point.ats and Delta_probe.starts (reluctance:4) since the spike would be included in the calculation of a delta. We'd rather not on Timer.records (r:3) since they are more liable to be in the middle of something performance sensitive. We're slightly more happy to calibrate after a Group.reset (r:2), but ideally want to calibrate on a call to safe_to_delay (r:1; lowest).

Here t specifies the kind of slow tasks to run if the reluctance has been overcome.