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

<h2>task_sample</h2>\r<hr>\r<p>\r<strong>Function</strong> - Sample the target task's thread program counters periodically.\r<h3>SYNOPSIS</h3>\r<pre>\r<strong>kern_return_t   task_sample</strong>\r                <strong>(task_t</strong>                             <var>sample_task</var>,\r                 <strong>mach_port_make_send_t</strong>               <var>reply_port</var><strong>);</strong>\r</pre>\r<h3>PARAMETERS</h3>\r<dl>\r<p>\r<dt> <var>sample_task</var> \r<dd>\r[in task send right]\rPort for the task whose threads' PC are to be\rsampled.\r<p>\r<dt> <var>reply_port</var> \r<dd>\r[in sample receive (to be converted to send) right]\rPort to which PC sample buffers are sent.  A value of <strong>MACH_PORT_NULL</strong> \rstops PC sampling for the task.\r</dl>\r<h3>DESCRIPTION</h3>\r<p>\rThe <strong>task_sample</strong> function causes the program counter (PC) of the \rspecified <var>sample_task</var> (actually, all of the threads within \r<var>sample_task</var>) to be sampled periodically (whenever one of the threads \rhappens to be running at the time of the kernel's "hardclock" interrupt).  \rThe set of PC sample values obtained are saved in buffers which are sent to \rthe specified <var>reply_port</var> in <strong>receive_samples</strong> messages.\r<h3>RETURN VALUES</h3>\r<p>\rOnly generic errors apply.\r<h3>RELATED INFORMATION</h3>\r<p>\rFunctions:\r<a href="thread_sample.html"><strong>thread_sample</strong></a>,\r<a href="receive_samples.html"><strong>receive_samples</strong></a>.\r