pthread_attr_getschedparam()--Get Thread Attributes Object Scheduling Parameters

 #include <pthread.h>
 #include <sched.h>
 int pthread_attr_getschedparam(const pthread_attr_t *attr,  
                               struct sched_param *param);  

The pthread_attr_getschedparam() function returns the scheduling parameters attribute from the thread attributes object. The default i5/OS scheduling policy is SCHED_OTHER and cannot be changed to another scheduling policy.

The sched_policy field of the param parameter is always returned as SCHED_OTHER. The sched_priority field of the param structure is set to the priority of the target thread at the time of the call.

Note: Do not use pthread_setschedparam() 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, pthread_getschedparam() returns only the information that was set by the pthread interfaces. (pthread_setschedparam() or modification of the thread attribute using pthread_attr_setschedparam()).

Authorities and Locks

None.

Parameters

attr

(Input) The address of the thread attributes object

param

(Output) The address of the variable to contain the returned scheduling parameters

Return Value

0

pthread_attr_getschedparam() was successful.

value

pthread_attr_getschedparam() was not successful. value is set to indicate the error condition.

Error Conditions

If pthread_attr_getschedparam() 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.

[EINVAL]

The value specified for the argument is not correct.

Related Information

• The <pthread.h> header file. See Header files for Pthread functions.
  
  
• The <sched.h> header file. See Header files for Pthread functions.
  
  
• pthread_attr_setschedparam()--Set Thread Attributes Object Scheduling Parameters.

Example

See Code disclaimer information for information pertaining to code examples.

#define _MULTI_THREADED
#include <pthread.h>
#include <sched.h>
#include <stdio.h>
#include "check.h"

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);

  printf("Get scheduling parameters\n");
  rc = pthread_attr_getschedparam(&pta, &param);
  checkResults("pthread_attr_getschedparam()\n", rc);

  printf("The thread attributes object indicates: ");
  printf("priority %d\n", param.sched_priority);

  printf("Destroy thread attributes object\n");
  rc = pthread_attr_destroy(&pta);
  checkResults("pthread_attr_destroy()\n", rc);

  printf("Main completed\n");
  return 0;
}

Output:

Enter Testcase - QP0WTEST/TAGSP0
Create a thread attributes object
Get scheduling parameters
The thread attributes object indicates: priority 0
Destroy thread attributes object
Main completed