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sched_yield(3)
NAME
  sched_yield - Signals scheduler a willingness to yield to another thread

SYNOPSIS
  #include <pthread.h>

  void sched_yield(
	  void );

LIBRARY
  DECthreads POSIX 1003.1c Library (libpthread.so)

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 forces the running thread to relinquish the processor until it
  again becomes the head of its thread list. 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 calling 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 sched_yield,
  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 sched_yield, other threads can be given the
  opportunity to run when the resources are free. This can sometimes improve
  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) that 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 degrade
  performance. For example, it is counter-productive for a thread to yield
  while it holds a resource that the threads to which it is yielding will
  need. Likewise, it is pointless to yield unless there is likely to be
  another thread that is ready to run.

RETURN VALUES
  None

SEE ALSO
  Functions: pthread_attr_setschedparam(3), pthread_setschedparam(3)

  Manuals: Guide to DECthreads and Programmer's Guide

Index for Section 3

Alphabetical listing for S

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