Macro: COMMON-LISP:TIME

Execute FORM and print timing information on TRACE-OUTPUT.

On some hardware platforms estimated processor cycle counts are included in this output; this number is slightly inflated, since it includes the pipeline involved in reading the cycle counter – executing (TIME NIL) a few times will give you an idea of the overhead, and its variance. The cycle counters are also per processor, not per thread: if multiple threads are running on the same processor, the reported counts will include cycles taken up by all threads running on the processor where TIME was executed. Furthermore, if the operating system migrates the thread to another processor between reads of the cycle counter, the results will be completely bogus. Finally, the counter is cycle counter, incremented by the hardware even when the process is halted – which is to say that cycles pass normally during operations like SLEEP.

Lambda list

(sb-kernel:form)