- current-jiffyprocedure
Returns the number of jiffies as an exact integer that have elapsed since an arbitrary, implementation-defined epoch. A jiffy is an implementation-defined fraction of a second which is defined by the return value of the jiffies-per-second procedure. The starting epoch is guaranteed to be constant during a run of the program, but may vary between runs.
Rationale: Jiffies are allowed to be implementation-dependent so that current-jiffy can execute with minimum overhead. It should be very likely that a compactly represented integer will suffice as the returned value. Any particular jiffy size will be inappropriate for some implementations: a microsecond is too long for a very fast machine, while a much smaller unit would force many implementations to return integers which have to be allocated for most calls, rendering current-jiffy less useful for accurate timing measurements.