* This is set by the scheduler at the beginning of its main loop. It may be
* used (read-only) from everywhere. As none of the functions called by the
* scheduler are allowed to block, this value should be accurate enough so that
* This is set by the scheduler at the beginning of its main loop. It may be
* used (read-only) from everywhere. As none of the functions called by the
* scheduler are allowed to block, this value should be accurate enough so that