sched_yield


SYNOPSIS
       #include <sched.h>

       int sched_yield(void);

DESCRIPTION
       sched_yield()  causes  the  calling  thread to relinquish the CPU.  The
       thread is moved to the end of the queue for its static priority  and  a
       new thread gets to run.

RETURN VALUE
       On  success,  sched_yield()  returns  0.  On error, -1 is returned, and
       errno is set appropriately.

ERRORS
       In the Linux implementation, sched_yield() always succeeds.

CONFORMING TO
       POSIX.1-2001.

NOTES
       If the calling thread is the only thread in the highest  priority  list
       at that time, it will continue to run after a call to sched_yield().

       POSIX  systems on which sched_yield() is available define _POSIX_PRIOR-
       ITY_SCHEDULING in <unistd.h>.

       Strategic calls to sched_yield()  can  improve  performance  by  giving
       other  threads  or  processes  a chance to run when (heavily) contended
       resources (e.g., mutexes) have been  released  by  the  caller.   Avoid
       calling  sched_yield()  unnecessarily  or  inappropriately  (e.g., when
       resources needed by other schedulable threads are  still  held  by  the
       caller),  since  doing  so will result in unnecessary context switches,
       which will degrade system performance.

SEE ALSO
       sched_setscheduler(2) for a description of Linux scheduling

       Programming for the real  world  -  POSIX.4  by  Bill  O.  Gallmeister,
       O'Reilly & Associates, Inc., ISBN 1-56592-074-0.

COLOPHON
       This  page  is  part of release 3.54 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.



Linux                             2008-10-18                    SCHED_YIELD(2)
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