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pthread_at...schedparam(3) Library Functions Manual pthread_at...schedparam(3) NAME pthread_attr_setschedparam - Changes the values of the parameters asso- ciated with a scheduling policy of the specified thread attributes ob- ject. LIBRARY DECthreads POSIX 1003.1c Library (libpthread.so) SYNOPSIS #include <pthread.h> int pthread_attr_setschedparam( pthread_attr_t *attr, const struct sched_param *param); STANDARDS Interfaces documented on this reference page conform to industry stan- dards as follows: IEEE Std 1003.1c-1995, POSIX System Application Program Interface PARAMETERS Thread attributes object for the scheduling policy whose parameters are to be set. A structure containing new values for scheduling parameters associated with the scheduling policy attribute of the specified thread attributes object. Note that DECthreads provides only the sched_prior- ity scheduling parameter. It allows specifying the scheduling prior- ity. See the Description section for information about this scheduling parameter. DESCRIPTION This routine sets the scheduling parameters associated with the sched- uling policy attribute of the thread attributes object specified by the attr argument. Use the sched_priority field of a sched_param structure to set a thread's execution priority. The effect of the scheduling priority you assign depends on the scheduling policy specified for the attributes object specified by the attr argument. By default, a created thread inherits the priority of the thread call- ing pthread_create(3). To specify a priority using this routine, scheduling inheritance must be disabled at the time the thread is cre- ated. Before calling pthread_create(3), call pthread_attr_setinher- itsched(3) and specify the value PTHREAD_EXPLICIT_SCHED for the inherit argument. An application specifies priority only to express the urgency of exe- cuting the thread relative to other threads. DO NOT USE PRIORITY TO CONTROL MUTUAL EXCLUSION WHEN ACCESSING SHARED DATA. With a sufficient number of processors present, all ready threads, regardless of prior- ity, execute simultaneously. Valid values of the sched_priority scheduling parameter depend on the chosen scheduling policy. Use the POSIX routines sched_get_prior- ity_min(3) or sched_get_priority_max(3) to determine the low and high limits of each policy. Additionally, DECthreads provides nonportable priority range constants, as follows: PRI_FIFO_MIN to PRI_FIFO_MAX PRI_RR_MIN to PRI_RR_MAX PRI_OTHER_MIN to PRI_OTHER_MAX PRI_FG_MIN_NP to PRI_FG_MAX_NP PRI_BG_MIN_NP to PRI_BG_MAX_NP The default priority varies by DECthreads platform. On DIGITAL UNIX, the default is 19 (that is, the POSIX priority of a normal timeshare process). On other platforms, the default priority is the midpoint be- tween PRI_FG_MIN_NP and PRI_FG_MAX_NP. RETURN VALUES If an error condition occurs, this routine returns an integer value in- dicating the type of error. Possible return values are as follows: Successful completion. The value specified by param is invalid. An attempt was made to set the attribute to an unsupported value. ERRORS None RELATED INFORMATION Functions: pthread_attr_init(3), pthread_attr_getschedparam(3), pthread_attr_setinheritsched(3), pthread_attr_setschedpolicy(3), pthread_create(3), sched_yield(3) Manuals: Guide to DECthreads and Programmer's Guide delim off pthread_at...schedparam(3)