Content-type: text/html Man page of pthread_setschedparam

pthread_setschedparam

Section: C Library Functions (3)
Index Return to Main Contents
 

NAME

pthread_setschedparam - Changes a thread's scheduling policy and scheduling parameters.  

LIBRARY

DECthreads POSIX 1003.1c Library (libpthread.so)  

SYNOPSIS

#include <pthread.h>

int pthread_setschedparam(
                   pthread_t                  thread,
                   int                        policy,
                   const struct sched_param   *param);  

STANDARDS

Interfaces documented on this reference page conform to industry standards as follows:

IEEE Std 1003.1c-1995, POSIX System Application Program Interface  

PARAMETERS

Thread whose scheduling policy and parameters are to be changed. New scheduling policy value for the thread specified in thread. The following are valid values: SCHED_BG_NP SCHED_FG_NP SCHED_FIFO SCHED_OTHER SCHED_RR See Guide to DECthreads for a description of the scheduling policies. New values of the scheduling parameters associated with the scheduling policy for the thread specified in thread. Valid values for the sched_priority field of a sched_param structure depend on the chosen scheduling policy. Use the POSIX routines sched_get_priority_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 (low) to PRI_FIFO_MAX (high) PRI_RR_MIN (low) to PRI_RR_MAX (high) PRI_OTHER_MIN (low) to PRI_OTHER_MAX (high) PRI_FG_MIN_NP (low) to PRI_FG_MAX_NP (high) PRI_BG_MIN_NP (low) to PRI_BG_MAX_NP (high) 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.

 

DESCRIPTION

This routine changes both the current scheduling policy and associated scheduling parameters of the thread specified by thread to the policy and associated parameters provided in policy and param, respectively.

All currently implemented DECthreads scheduling policies have one scheduling parameter called sched_priority. For the policy you choose, you must specify an appropriate value in the sched_priority field of the sched_param structure.

Changing the scheduling policy or priority, or both, of a thread can cause it to start executing or to be preempted by another thread. A thread changes its own scheduling policy and priority by using the handle returned by the pthread_self(3) routine.

This routine differs from pthread_attr_setschedpolicy(3) and pthread_attr_setschedparam(3), in that those routines set the scheduling policy and parameter attributes that are used to establish the scheduling priority and scheduling policy of a new thread when it is created. However, this routine changes the scheduling policy and parameters of an existing thread.

 

RETURN VALUES

If an error condition occurs, no scheduling policy or parameters are changed for the target thread, and this routine returns an integer value indicating the type of error. Possible return values are as follows: Successful completion. The value specified by policy or param is invalid. An attempt was made to set the scheduling policy or a parameter to an unsupported value. The caller does not have the appropriate privileges to set the scheduling policy or parameters of the specified thread. The value specified by thread does not refer to an existing thread.  

ERRORS

None  

RELATED INFORMATION

Functions: pthread_attr_setschedparam(3), pthread_attr_setschedpolicy(3), pthread_create(3), pthread_self(3), sched_yield(3)

Manuals: Guide to DECthreads and Programmer's Guide

delim off


 

Index

NAME
LIBRARY
SYNOPSIS
STANDARDS
PARAMETERS
DESCRIPTION
RETURN VALUES
ERRORS
RELATED INFORMATION

This document was created by man2html, using the manual pages.
Time: 02:40:59 GMT, October 02, 2010