destructuring-bindとletの速度比較

はじめに

destructuring-bindとletで速度比較をしました。

ソースコード

(defmacro with-bench ((&optional (num-repeat 10000000))
                      &body body)
  `(time (loop repeat ,num-repeat do (progn ,@body))))


(defun dbind-test ()
  (let ((list (list 1 2 3)))
    (with-bench ()
      (destructuring-bind (x y z) list
        (+ x y z)))))

(defun let-test ()
  (let ((list (list 1 2 3)))
    (with-bench ()
      (let ((x (first list))
            (y (second list))
            (z (third list)))
        (+ x y z)))))

結果

• dbind-test: 約3.9秒
• let-test: 約0.12秒

CL-USER> (dbind-test)
Evaluation took:
  3.899 seconds of real time
  3.863381 seconds of total run time (3.829654 user, 0.033727 system)
  99.08% CPU
  9,716,958,684 processor cycles
  4,016 bytes consed

NIL
CL-USER> (dbind-test)
Evaluation took:
  3.914 seconds of real time
  3.878260 seconds of total run time (3.841974 user, 0.036286 system)
  99.08% CPU
  9,751,604,518 processor cycles
  33,072 bytes consed

NIL
CL-USER> (dbind-test)
Evaluation took:
  3.864 seconds of real time
  3.827455 seconds of total run time (3.792557 user, 0.034898 system)
  99.04% CPU
  9,629,652,079 processor cycles
  32,768 bytes consed

NIL
CL-USER> (let-test)
Evaluation took:
  0.125 seconds of real time
  0.108741 seconds of total run time (0.107721 user, 0.001020 system)
  87.20% CPU
  311,094,075 processor cycles
  0 bytes consed

NIL
CL-USER> (let-test)
Evaluation took:
  0.122 seconds of real time
  0.105200 seconds of total run time (0.103102 user, 0.002098 system)
  86.07% CPU
  304,988,627 processor cycles
  0 bytes consed

NIL
CL-USER> (let-test)
Evaluation took:
  0.118 seconds of real time
  0.100798 seconds of total run time (0.100035 user, 0.000763 system)
  85.59% CPU
  293,909,444 processor cycles
  0 bytes consed

NIL