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NAME

       sched_yield - yield the processor

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_PRIORITY_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 3.24 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/.