osf1 man page for pthread_yield_np

pthread_yield_np(3)					     Library Functions Manual					       pthread_yield_np(3)

NAME
       pthread_yield_np  -  Notifies  the  scheduler  that  the current thread is willing to release its processor to other threads of the same or
       higher priority.

LIBRARY
       DECthreads POSIX 1003.1c Library (libpthread.so)

SYNOPSIS
       #include <pthread.h>

       int pthread_yield_np(
			 void);

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

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

PARAMETERS
       None

DESCRIPTION
       This routine notifies the thread scheduler that the current thread is willing to release its processor to other threads	of  equivalent	or
       greater	scheduling precedence. (A thread generally will release its processor to a thread of a greater scheduling precedence without call-
       ing this routine.)  If no other threads of equivalent or greater scheduling precedence are ready to execute, the thread continues.

       This routine can allow knowledge of the details of an application to be used to improve	its  performance.   If	a  thread  does  not  call
       pthread_yield_np(3), other threads may be given the opportunity to run at arbitrary points (possibly even when the interrupted thread holds
       a required resource).  By making strategic calls to pthread_yield_np(3), other threads may  be  given  the  opportunity	to  run  when  the
       resources are free.  This improves performance by reducing contention for the resource.

       As  a  general guideline, consider calling this routine after a thread has released a resource (such as a mutex) which is heavily contended
       for by other threads.  This can be especially important if the program is running on a uniprocessor machine, or if the thread acquires  and
       releases the resource inside a tight loop.

       Use  this routine carefully and sparingly, because misuse can cause unnecessary context switching which will increase overhead and actually
       degrade performance.  For example, it is counter-productive for a thread to yield while it holds a resource which the threads to  which	it
       is yielding will need.  Likewise, it is pointless to yield unless there is likely to be another thread which is ready to run.

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 routine is not supported by this implementation.

ERRORS
       None

RELATED INFORMATION
       Functions: pthread_attr_setschedparam(3), pthread_setschedparam(3), pthread_getscheduler(3)

       Manuals: Guide to DECthreads and Programmer's Guide

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															       pthread_yield_np(3)