pthread_attr_setschedparam(3)pthread_attr_setschedparam(3)NAMEpthread_attr_setschedparam - Changes the values of the parameters asso‐
ciated with a scheduling policy of the specified thread attributes
object
SYNOPSIS
#include <pthread.h>
int pthread_attr_setschedparam(
pthread_attr_t *attr,
const struct sched_param *param );
LIBRARY
DECthreads POSIX 1003.1c Library (libpthread.so)
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. 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, sched‐
uling inheritance must be disabled at the time the thread is created.
Before calling pthread_create(3), call pthread_attr_setinheritsched(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 Tru64 UNIX, the
default is 19 (that is, the POSIX priority of a normal timeshare
process). On other platforms, the default priority is the midpoint
between PRI_FG_MIN_NP and PRI_FG_MAX_NP.
RETURN VALUES
If an error condition occurs, this routine returns an integer value
indicating the type of error. Possible return values are as follows:
Successful completion. The value specified by param is not a valid
thread attributes object, or the value specified by param is invalid.
An attempt was made to set the attribute to an unsupported value.
ERRORS
None
SEE ALSO
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
pthread_attr_setschedparam(3)
