Macro

Summary

Determines the execution time of a form in the current environment.

Package

common-lisp

Signature

time form => result

Arguments

form

A form to be evaluated

Values

result

The result of the evaluation of the form.

Description

time can be used to determine execution times. The macro evaluates the form given to it as argument, and prints out some timing and size data: the user and system times (in seconds), the elapsed time (in hours, minutes and seconds), and the total amount of heap space allocated in executing the form (in bytes).

The timing and size data covers all stack groups, not just the one that invokes time . Note that time itself uses a small, constant amount of heap space.

Note: time measures all threads, so to test accurately for consing in your code code you need to do:

(without-interrupts (time code ))

This is particularly important when using the Common LispWorks IDE.

Examples

CL-USER 33 > (time (progn (format t "start")

                   (dotimes (a 100) nil)

                   (format t "end")))

Timing the evaluation of (PROGN (FORMAT T "start") (DOTIMES (A 100) NIL) (FORMAT T "end"))

startend

User time    =        0.000

System time  =        0.000

Elapsed time =        0.000

Allocation   = 5468 bytes

0 Page faults

Calls to %EVAL    1160

NIL

See also

extended-time