[apple/xnu.git] / osfmk / man / task_policy.html

<h2>task_policy</h2>\r<hr>\r<p>\r<strong>Function</strong> - Set target task's default scheduling policy state.\r<h3>SYNOPSIS</h3>\r<pre>\r<strong>kern_return_t   task_policy</strong>\r                <strong>(task_t</strong>                                    <var>task</var>,\r                 <strong>policy_t</strong>                                <var>policy</var>,\r                 <strong>policy_base_t</strong>                             <var>base</var>,\r                 <strong>base</strong>                                <var>base_count</var>,\r                 <strong>boolean_t</strong>                            <var>set_limit</var>,\r                 <strong>boolean_t</strong>                       <var>change_threads</var><strong>);</strong>\r</pre>\r<h3>PARAMETERS</h3>\r<dl>\r<dt> <var>task</var> \r<dd>\r[in task send right]\rThe port for the task whose scheduling attributes \rare to be set.\r<dt> <var>policy</var> \r<dd>\r[in scalar]\rDefault policy.  The values currently defined are <strong>POLICY_TIMESHARE</strong>, \r<strong>POLICY_RR</strong> (round robin) and <strong>POLICY_FIFO</strong> (firstin, first-out).\r<dt> <var>base</var> \r<dd>\r[pointer to in structure]\rBase scheduling policy data, <strong>policy_fifo_base</strong>, \r<strong>policy_rr_base</strong> or <strong>policy_timeshare_base</strong>.\r<dt> <var>base_count</var> \r<dd>\r[in scalar]\rThe size of the buffer (in natural-sized units).\r<dt> <var>set_limit</var> \r<dd>\r[in scalar]\rTrue if the scheduling limits for the task should be restricted \rto allow no more service than specified by <var>base</var>.\r<dt> <var>change_threads</var> \r<dd>\r[in scalar]\rTrue if the attributes (and limits, if <var>set_limit</var> is true) of\rexisting threads within the task should also be changed.\r</dl>\r<h3>DESCRIPTION</h3>\r<p>\rThe <strong>task_policy</strong> function sets the default scheduling\rattributes for <var>task</var>.  These \rattributes are used when creating new threads.  Changing the default attributes \rfor a task does not affect the attributes of the contained threads unless \r<var>change_threads</var> is <strong>TRUE</strong>.  At no time will a thread ever have \rscheduling attributes that exceed the thread's limits.\r<h3>RETURN VALUES</h3>\r<dl>\r<dt> <strong>KERN_INVALID_POLICY</strong>\r<dd>\rThe processor set does not currently enable <var>policy</var>.\r<dt> <strong>KERN_POLICY_LIMIT</strong>\r<dd>\rThe specified scheduling attributes exceeds the thread's limits.\r</dl>\r<h3>RELATED INFORMATION</h3>\r<p>\rFunctions:\r<a href="thread_policy.html"><strong>thread_policy</strong></a>,\r<a href="thread_set_policy.html"><strong>thread_set_policy</strong></a>,\r<a href="task_set_policy.html"><strong>task_set_policy</strong></a>,\r<a href="P_set_policy_control.html"><strong>processor_set_policy_control</strong></a>.\r<p>\rData Structures:\r<a href="policy_fifo_info.html"><strong>policy_fifo_info</strong></a>,\r<a href="policy_rr_info.html"><strong>policy_rr_info</strong></a>,\r<a href="policy_timeshare_info.html"><strong>policy_timeshare_info</strong></a>.\r