Profile.html 6.4 KB

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  57. <a name="Profile-1"></a>
  58. <h4 class="subsubsection">2.7.7.3 Profile</h4>
  59. <p>The virtual machine supports a profiling capability by way of this
  60. <a name="index-profile_002etxt-1"></a>
  61. feature. Profiling an application causes run time statistics about it to
  62. be written to a file &lsquo;<tt>./profile.txt</tt>&rsquo;. Profiled applications are of
  63. the form indicated in the following theorem
  64. </p>
  65. <dl compact="compact">
  66. <dt> <em>T12</em></dt>
  67. <dd><p>[[<code>profile</code>]] <code>(<var>f</var>,<var>s</var>)</code> = <code>((nil,nil),((nil,nil),(nil,((<var>f</var>,<var>s</var>),nil))))</code>
  68. </p></dd>
  69. </dl>
  70. <p>where <code><var>f</var></code> stands for the virtual code of the application, and
  71. <code><var>s</var></code> stands for the name of it to be written to the file.
  72. The semantics of a profiled function is identical to the unprofiled
  73. form for any non-<code>nil</code> <code><var>f</var></code>.
  74. </p>
  75. <dl compact="compact">
  76. <dt> <em>P9</em></dt>
  77. <dd><p>([[<code>profile</code>]] <code>(<var>f</var>,<var>s</var>)</code>) <code><var>x</var></code> = <code><var>f</var> <var>x</var></code>
  78. </p></dd>
  79. </dl>
  80. <p>Unlike the situation with <code>note</code>, the annotation <code><var>s</var></code> of
  81. <a name="index-note-1"></a>
  82. used in profiled code is not in an unrestricted format but must be a
  83. character string in the standard representation (as in
  84. <a href="Representation-of-Numeric-and-Textual-Data.html#Representation-of-Numeric-and-Textual-Data">Representation of Numeric and Textual Data</a>),
  85. because this string needs to be written by <code>avram</code> to the file
  86. &lsquo;<tt>./profile.txt</tt>&rsquo;. Ordinarily this string will be the source code
  87. identifier of the function being profiled.
  88. </p>
  89. <p>When profiles are used in many parts of an application, an informative
  90. table is generated showing the time spent in each part.
  91. </p>
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