Name

pthread_attr_setprio − Changes the scheduling priority attribute of thread creation. 

Syntax

#include <pthread.h>

int pthread_attr_setprio (attr, priority)
pthread_attr_t *attr;
int priority;

Arguments

attr Thread attributes object modified. 

priority New value for the priority attribute. The priority attribute is dependent upon scheduling policy.  Valid values fall within one of the following three ranges. 

The default priority is the midpoint between PRI_OTHER_MIN and PRI_OTHER_MAX. (<REFERENCE>(sched_sec) describes how to specify priorities between the minimum and maximum values.) 

Description

This routine sets the execution priority of threads that are created using the attributes object specified by the attr argument. 

By default, a created thread inherits the priority of the thread calling pthread_create. To specify a priority using this routine, scheduling inheritance must be disabled at the time the thread is created.  Call pthread_attr_setinheritsched and specify the value DEFAULT_SCHED for the inherit argument before calling this routine and pthread_create. 

An application specifies  priority only to express the urgency of executing the thread relative to other threads. Priority is not used to control mutual exclusion when accessing shared data.  With a sufficient number of processors executing, all ready threads, regardless of priority, execute simultaneously. 

Return Values

If an error condition occurs, this routine returns -1 and sets errno to the corresponding error value.  Possible return values are as follows.