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<title>pthread_attr_setschedparam()--Set Thread Attributes Object Scheduling
Parameters</title>
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<h2>pthread_attr_setschedparam()--Set Thread Attributes Object Scheduling
Parameters</h2>
<div class="box" style="width: 60%;">
<br>
Syntax:
<pre>
#include <pthread.h>
#include <sched.h>
int pthread_attr_setschedparam(pthread_attr_t *attr,
const struct sched_param *param);
</pre>
Service Program Name: QP0WPTHR<br>
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Default Public Authority: *USE <br>
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<br>
Threadsafe: Yes<br>
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<br>
Signal Safe: Yes<br>
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<br>
</div>
<p>The <strong>pthread_attr_setschedparam</strong>() function sets the
scheduling parameters in the thread attributes object. The supported i5/OS
scheduling policy is <strong>SCHED_OTHER.</strong> Attempting to set the
<em>sched_policy</em> field of the <em>param</em> parameter other than
<strong>SCHED_OTHER</strong> causes the <strong>EINVAL</strong> error. The
<em>sched_priority</em> field of the <em>param</em> parameter must range from
<strong>PRIORITY_MIN</strong> to <strong>PRIORITY_MAX</strong> or the
<strong>ENOTSUP</strong> error occurs.</p>
<p>All reserved fields in the scheduling parameters structure must be binary
zero or the <strong>EINVAL</strong> error occurs.</p>
<p><strong>Note:</strong> Do not use <strong>pthread_setschedparam</strong>()
to set the priority of a thread if you also use another mechanism (outside of
the pthread APIs) to set the priority of a thread. If you do,
<strong>pthread_getschedparam</strong>() returns only that information that was
set by the pthread interfaces (<strong>pthread_setschedparam</strong>() or
modification of the thread attribute using
<strong>pthread_attr_setschedparam</strong>()).</p>
<br>
<h3>Authorities and Locks</h3>
<p>None.</p>
<br>
<h3>Parameters</h3>
<dl>
<dt><strong>attr</strong></dt>
<dd>(Input/Output) The address of the thread attributes object</dd>
<dt><strong>param</strong></dt>
<dd>(Input) Address of the variable containing the scheduling parameters</dd>
</dl>
<br>
<h3>Return Value</h3>
<dl>
<dt><strong>0</strong></dt>
<dd><strong>pthread_attr_setschedparam</strong>() was successful.</dd>
<dt><strong>value</strong></dt>
<dd><strong>pthread_attr_setschedparam</strong>() was not successful.
<em>value</em> is set to indicate the error condition.</dd>
</dl>
<br>
<h3>Error Conditions</h3>
<p>If <strong>pthread_attr_setschedparam</strong>() was not successful, the
error condition returned usually indicates one of the following errors. Under
some conditions, the value returned could indicate an error other than those
listed here.</p>
<dl>
<dt><em>[EINVAL]</em></dt>
<dd><p>The value specified for the argument is not correct.</p></dd>
<dt><em>[ENOTSUP]</em></dt>
<dd><p>The value specified for the priority argument is not supported.</p></dd>
</dl>
<br>
<h3>Related Information</h3>
<ul>
<li>The <<strong>pthread.h</strong>> header file. See <a href=
"rzah4hed.htm">Header files for Pthread functions</a>.<br><br></li>
<li>The <<strong>sched.h</strong>> header file. See <a href=
"rzah4hed.htm">Header files for Pthread functions</a>.<br><br></li>
<li><a href="users_g8.htm">pthread_attr_getschedparam()</a>--Get Thread Attributes
Object Scheduling Parameters</li>
</ul>
<br>
<h3>Example</h3>
<p>See <a href="../apiref/aboutapis.htm#codedisclaimer">Code disclaimer information</a>
for information pertaining to code examples.</p>
<pre>
#define _MULTI_THREADED
#include <pthread.h>
#include <sched.h>
#include <stdio.h>
#include "check.h"
#define BUMP_PRIO 1
static int thePriority = 0;
void showSchedParam(pthread_attr_t *a)
{
int rc=0;
struct sched_param param;
printf("Get scheduling parameters\n");
rc = pthread_attr_getschedparam(a, &param);
checkResults("pthread_attr_getschedparam()\n", rc);
printf("The thread attributes object indicates priority: %d\n",
param.sched_priority);
thePriority = param.sched_priority;
return;
}
int main(int argc, char **argv)
{
pthread_t thread;
int rc=0;
pthread_attr_t pta;
struct sched_param param;
printf("Enter Testcase - %s\n", argv[0]);
printf("Create a thread attributes object\n");
rc = pthread_attr_init(&pta);
checkResults("pthread_attr_init()\n", rc);
showSchedParam(&pta);
memset(&param, 0, sizeof(param));
if (thePriority + BUMP_PRIO <= PRIORITY_MAX_NP) {
param.sched_priority = thePriority + BUMP_PRIO;
}
printf("Setting scheduling parameters\n");
rc = pthread_attr_setschedparam(&pta, &param);
checkResults("pthread_attr_setschedparam()\n", rc);
showSchedParam(&pta);
printf("Destroy thread attributes object\n");
rc = pthread_attr_destroy(&pta);
checkResults("pthread_attr_destroy()\n", rc);
printf("Main completed\n");
return 0;
}
</pre>
<p><strong>Output:</strong></p>
<pre>
Enter Testcase - QP0WTEST/TASSP0
Create a thread attributes object
Get scheduling parameters
The thread attributes object indicates priority: 0
Setting scheduling parameters
Get scheduling parameters
The thread attributes object indicates priority: 0
Destroy thread attributes object
Main completed
</pre><br>
<hr>
API introduced: V4R3
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