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| 54 | <H2><A NAME="SECTION00101420000000000000000"> |
| 55 | 8.14.2 Resource Usage</A> |
| 56 | </H2> |
| 57 | |
| 58 | <P> |
| 59 | These functions are used to retrieve resource usage information: |
| 60 | |
| 61 | <P> |
| 62 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 63 | <td><nobr><b><tt id='l2h-3071' xml:id='l2h-3071' class="function">getrusage</tt></b>(</nobr></td> |
| 64 | <td><var>who</var>)</td></tr></table></dt> |
| 65 | <dd> |
| 66 | This function returns an object that describes the resources |
| 67 | consumed by either the current process or its children, as specified |
| 68 | by the <var>who</var> parameter. The <var>who</var> parameter should be |
| 69 | specified using one of the <tt class="constant">RUSAGE_*</tt> constants described |
| 70 | below. |
| 71 | |
| 72 | <P> |
| 73 | The fields of the return value each describe how a particular system |
| 74 | resource has been used, e.g. amount of time spent running is user mode |
| 75 | or number of times the process was swapped out of main memory. Some |
| 76 | values are dependent on the clock tick internal, e.g. the amount of |
| 77 | memory the process is using. |
| 78 | |
| 79 | <P> |
| 80 | For backward compatibility, the return value is also accessible as |
| 81 | a tuple of 16 elements. |
| 82 | |
| 83 | <P> |
| 84 | The fields <tt class="member">ru_utime</tt> and <tt class="member">ru_stime</tt> of the return value |
| 85 | are floating point values representing the amount of time spent |
| 86 | executing in user mode and the amount of time spent executing in system |
| 87 | mode, respectively. The remaining values are integers. Consult the |
| 88 | <span class="manpage"><i>getrusage</i>(2)</span> man page for detailed information about these |
| 89 | values. A brief summary is presented here: |
| 90 | |
| 91 | <P> |
| 92 | <div class="center"><table class="realtable"> |
| 93 | <thead> |
| 94 | <tr> |
| 95 | <th class="right" >Index</th> |
| 96 | <th class="left" >Field</th> |
| 97 | <th class="left" >Resource</th> |
| 98 | </tr> |
| 99 | </thead> |
| 100 | <tbody> |
| 101 | <tr><td class="right" valign="baseline"><code>0</code></td> |
| 102 | <td class="left" ><tt class="member">ru_utime</tt></td> |
| 103 | <td class="left" >time in user mode (float)</td></tr> |
| 104 | <tr><td class="right" valign="baseline"><code>1</code></td> |
| 105 | <td class="left" ><tt class="member">ru_stime</tt></td> |
| 106 | <td class="left" >time in system mode (float)</td></tr> |
| 107 | <tr><td class="right" valign="baseline"><code>2</code></td> |
| 108 | <td class="left" ><tt class="member">ru_maxrss</tt></td> |
| 109 | <td class="left" >maximum resident set size</td></tr> |
| 110 | <tr><td class="right" valign="baseline"><code>3</code></td> |
| 111 | <td class="left" ><tt class="member">ru_ixrss</tt></td> |
| 112 | <td class="left" >shared memory size</td></tr> |
| 113 | <tr><td class="right" valign="baseline"><code>4</code></td> |
| 114 | <td class="left" ><tt class="member">ru_idrss</tt></td> |
| 115 | <td class="left" >unshared memory size</td></tr> |
| 116 | <tr><td class="right" valign="baseline"><code>5</code></td> |
| 117 | <td class="left" ><tt class="member">ru_isrss</tt></td> |
| 118 | <td class="left" >unshared stack size</td></tr> |
| 119 | <tr><td class="right" valign="baseline"><code>6</code></td> |
| 120 | <td class="left" ><tt class="member">ru_minflt</tt></td> |
| 121 | <td class="left" >page faults not requiring I/O</td></tr> |
| 122 | <tr><td class="right" valign="baseline"><code>7</code></td> |
| 123 | <td class="left" ><tt class="member">ru_majflt</tt></td> |
| 124 | <td class="left" >page faults requiring I/O</td></tr> |
| 125 | <tr><td class="right" valign="baseline"><code>8</code></td> |
| 126 | <td class="left" ><tt class="member">ru_nswap</tt></td> |
| 127 | <td class="left" >number of swap outs</td></tr> |
| 128 | <tr><td class="right" valign="baseline"><code>9</code></td> |
| 129 | <td class="left" ><tt class="member">ru_inblock</tt></td> |
| 130 | <td class="left" >block input operations</td></tr> |
| 131 | <tr><td class="right" valign="baseline"><code>10</code></td> |
| 132 | <td class="left" ><tt class="member">ru_oublock</tt></td> |
| 133 | <td class="left" >block output operations</td></tr> |
| 134 | <tr><td class="right" valign="baseline"><code>11</code></td> |
| 135 | <td class="left" ><tt class="member">ru_msgsnd</tt></td> |
| 136 | <td class="left" >messages sent</td></tr> |
| 137 | <tr><td class="right" valign="baseline"><code>12</code></td> |
| 138 | <td class="left" ><tt class="member">ru_msgrcv</tt></td> |
| 139 | <td class="left" >messages received</td></tr> |
| 140 | <tr><td class="right" valign="baseline"><code>13</code></td> |
| 141 | <td class="left" ><tt class="member">ru_nsignals</tt></td> |
| 142 | <td class="left" >signals received</td></tr> |
| 143 | <tr><td class="right" valign="baseline"><code>14</code></td> |
| 144 | <td class="left" ><tt class="member">ru_nvcsw</tt></td> |
| 145 | <td class="left" >voluntary context switches</td></tr> |
| 146 | <tr><td class="right" valign="baseline"><code>15</code></td> |
| 147 | <td class="left" ><tt class="member">ru_nivcsw</tt></td> |
| 148 | <td class="left" >involuntary context switches</td></tr></tbody> |
| 149 | </table></div> |
| 150 | |
| 151 | <P> |
| 152 | This function will raise a <tt class="exception">ValueError</tt> if an invalid |
| 153 | <var>who</var> parameter is specified. It may also raise |
| 154 | <tt class="exception">error</tt> exception in unusual circumstances. |
| 155 | |
| 156 | <P> |
| 157 | |
| 158 | <span class="versionnote">Changed in version 2.3: |
| 159 | Added access to values as attributes of the |
| 160 | returned object.</span> |
| 161 | |
| 162 | </dl> |
| 163 | |
| 164 | <P> |
| 165 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 166 | <td><nobr><b><tt id='l2h-3072' xml:id='l2h-3072' class="function">getpagesize</tt></b>(</nobr></td> |
| 167 | <td><var></var>)</td></tr></table></dt> |
| 168 | <dd> |
| 169 | Returns the number of bytes in a system page. (This need not be the |
| 170 | same as the hardware page size.) This function is useful for |
| 171 | determining the number of bytes of memory a process is using. The |
| 172 | third element of the tuple returned by <tt class="function">getrusage()</tt> describes |
| 173 | memory usage in pages; multiplying by page size produces number of |
| 174 | bytes. |
| 175 | </dl> |
| 176 | |
| 177 | <P> |
| 178 | The following <tt class="constant">RUSAGE_*</tt> symbols are passed to the |
| 179 | <tt class="function">getrusage()</tt> function to specify which processes information |
| 180 | should be provided for. |
| 181 | |
| 182 | <P> |
| 183 | <dl><dt><b><tt id='l2h-3073' xml:id='l2h-3073'>RUSAGE_SELF</tt></b></dt> |
| 184 | <dd> |
| 185 | <tt class="constant">RUSAGE_SELF</tt> should be used to |
| 186 | request information pertaining only to the process itself. |
| 187 | </dd></dl> |
| 188 | |
| 189 | <P> |
| 190 | <dl><dt><b><tt id='l2h-3074' xml:id='l2h-3074'>RUSAGE_CHILDREN</tt></b></dt> |
| 191 | <dd> |
| 192 | Pass to <tt class="function">getrusage()</tt> to request resource information for |
| 193 | child processes of the calling process. |
| 194 | </dd></dl> |
| 195 | |
| 196 | <P> |
| 197 | <dl><dt><b><tt id='l2h-3075' xml:id='l2h-3075'>RUSAGE_BOTH</tt></b></dt> |
| 198 | <dd> |
| 199 | Pass to <tt class="function">getrusage()</tt> to request resources consumed by both |
| 200 | the current process and child processes. May not be available on all |
| 201 | systems. |
| 202 | </dd></dl> |
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