Comparing efficiency of READ-BYTE with READ-SEQUENCE.

read.lisp

(require :sb-sprof)

(defun test-read-byte0 ()
  (with-open-file (in "data" :direction :input
                             :element-type '(unsigned-byte 8))
    (loop repeat (* 4 1024 1024)
       do (read-byte in))))

(defun profile-read-byte0 ()
  (sb-sprof:with-profiling (:max-samples 100
                            :report :graph
                            :loop t)
    (test-read-byte0)))

(defun test-read-byte ()
  (with-open-file (out "/dev/null" :direction :output
                                   :if-exists :supersede
                                   :element-type '(unsigned-byte 8))
    (with-open-file (in "data" :direction :input
                               :element-type '(unsigned-byte 8))
      (loop repeat (* 4 1024 1024)
         do (write-byte (read-byte in) out)))))

(defun profile-read-byte ()
  (sb-sprof:with-profiling (:max-samples 100
                            :report :graph
                            :loop t)
    (test-read-byte)))

(defun test-read-sequence ()
  (with-open-file (out "/dev/null" :direction :output
                                   :if-exists :supersede
                                   :element-type '(unsigned-byte 8))
    (with-open-file (in "data" :direction :input
                               :element-type '(unsigned-byte 8))
      (let ((buf (make-array 1024 :element-type '(unsigned-byte 8))))
        (loop repeat (* 4 1024)
           do (read-sequence buf in :end 1024)
              (write-sequence buf out :end 1024)))))
  nil)

(defun profile-read-sequence ()
  (sb-sprof:with-profiling (:max-samples 100
                            :report :graph
                            :loop t)
    (test-read-sequence)))