osfmk/man/task_policy.html

   1 <h2>task_policy</h2>
   2 <hr>
   3 <p>
   4 <strong>Function</strong> - Set target task's default scheduling policy state.
   5 <h3>SYNOPSIS</h3>
   6 <pre>
   7 <strong>kern_return_t   task_policy</strong>
   8                 <strong>(task_t</strong>                                    <var>task</var>,
   9                  <strong>policy_t</strong>                                <var>policy</var>,
  10                  <strong>policy_base_t</strong>                             <var>base</var>,
  11                  <strong>base</strong>                                <var>base_count</var>,
  12                  <strong>boolean_t</strong>                            <var>set_limit</var>,
  13                  <strong>boolean_t</strong>                       <var>change_threads</var><strong>);</strong>
  14 </pre>
  15 <h3>PARAMETERS</h3>
  16 <dl>
  17 <dt> <var>task</var>
  18 <dd>
  19 [in task send right]
  20 The port for the task whose scheduling attributes
  21 are to be set.
  22 <dt> <var>policy</var>
  23 <dd>
  24 [in scalar]
  25 Default policy.  The values currently defined are <strong>POLICY_TIMESHARE</strong>,
  26 <strong>POLICY_RR</strong> (round robin) and <strong>POLICY_FIFO</strong> (firstin, first-out).
  27 <dt> <var>base</var>
  28 <dd>
  29 [pointer to in structure]
  30 Base scheduling policy data, <strong>policy_fifo_base</strong>,
  31 <strong>policy_rr_base</strong> or <strong>policy_timeshare_base</strong>.
  32 <dt> <var>base_count</var>
  33 <dd>
  34 [in scalar]
  35 The size of the buffer (in natural-sized units).
  36 <dt> <var>set_limit</var>
  37 <dd>
  38 [in scalar]
  39 True if the scheduling limits for the task should be restricted
  40 to allow no more service than specified by <var>base</var>.
  41 <dt> <var>change_threads</var>
  42 <dd>
  43 [in scalar]
  44 True if the attributes (and limits, if <var>set_limit</var> is true) of
  45 existing threads within the task should also be changed.
  46 </dl>
  47 <h3>DESCRIPTION</h3>
  48 <p>
  49 The <strong>task_policy</strong> function sets the default scheduling
  50 attributes for <var>task</var>.  These
  51 attributes are used when creating new threads.  Changing the default attributes
  52 for a task does not affect the attributes of the contained threads unless
  53 <var>change_threads</var> is <strong>TRUE</strong>.  At no time will a thread ever have
  54 scheduling attributes that exceed the thread's limits.
  55 <h3>RETURN VALUES</h3>
  56 <dl>
  57 <dt> <strong>KERN_INVALID_POLICY</strong>
  58 <dd>
  59 The processor set does not currently enable <var>policy</var>.
  60 <dt> <strong>KERN_POLICY_LIMIT</strong>
  61 <dd>
  62 The specified scheduling attributes exceeds the thread's limits.
  63 </dl>
  64 <h3>RELATED INFORMATION</h3>
  65 <p>
  66 Functions:
  67 <a href="thread_policy.html"><strong>thread_policy</strong></a>,
  68 <a href="thread_set_policy.html"><strong>thread_set_policy</strong></a>,
  69 <a href="task_set_policy.html"><strong>task_set_policy</strong></a>,
  70 <a href="P_set_policy_control.html"><strong>processor_set_policy_control</strong></a>.
  71 <p>
  72 Data Structures:
  73 <a href="policy_fifo_info.html"><strong>policy_fifo_info</strong></a>,
  74 <a href="policy_rr_info.html"><strong>policy_rr_info</strong></a>,
  75 <a href="policy_timeshare_info.html"><strong>policy_timeshare_info</strong></a>.