pthread_attr_setschedparam()--Set Thread Attributes Object Scheduling Parameters
Syntax:
#include <pthread.h> #include <sched.h> int pthread_attr_setschedparam(pthread_attr_t *attr, const struct sched_param *param);Service Program Name: QP0WPTHR
Default Public Authority: *USE
Threadsafe: Yes
Signal Safe: Yes
The pthread_attr_setschedparam() function sets the scheduling parameters in the thread attributes object. The supported IBM® i scheduling policy is SCHED_OTHER. Attempting to set the sched_policy field of the param parameter other than SCHED_OTHER causes the EINVAL error. The sched_priority field of the param parameter must range from PRIORITY_MIN to PRIORITY_MAX or the ENOTSUP error occurs.
All reserved fields in the scheduling parameters structure must be binary zero or the EINVAL error occurs.
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 that 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/Output) The address of the thread attributes object
- param
- (Input) Address of the variable containing the scheduling parameters
Return Value
- 0
- pthread_attr_setschedparam() was successful.
- value
- pthread_attr_setschedparam() was not successful. value is set to indicate the error condition.
Error Conditions
If pthread_attr_setschedparam() 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.
- [ENOTSUP]
The value specified for the priority argument is not supported.
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_getschedparam()--Get Thread Attributes Object Scheduling Parameters
Example
Note: By using the code examples, you agree to the terms of the Code license and disclaimer information.
#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, ¶m); 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(¶m, 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, ¶m); 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; }
Output:
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
API introduced: V4R3
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