sched_yield(2)

1sched_yield(2)                System Calls Manual               sched_yield(2)
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NAME

6       sched_yield - yield the processor
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LIBRARY

9       Standard C library (libc, -lc)
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SYNOPSIS

12       #include <sched.h>
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14       int sched_yield(void);
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DESCRIPTION

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

22       On success, sched_yield() returns 0.  On error, -1 is returned, and er‐
23       rno is set to indicate the error.
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ERRORS

26       In the Linux implementation, sched_yield() always succeeds.
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STANDARDS

29       POSIX.1-2008.
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HISTORY

32       POSIX.1-2001.
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NOTES

35       If the calling thread is the only thread in the highest  priority  list
36       at that time, it will continue to run after a call to sched_yield().
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38       POSIX  systems on which sched_yield() is available define _POSIX_PRIOR‐
39       ITY_SCHEDULING in <unistd.h>.
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41       Strategic calls to sched_yield()  can  improve  performance  by  giving
42       other threads or processes a chance to run when (heavily) contended re‐
43       sources (e.g., mutexes) have been released by the caller.  Avoid  call‐
44       ing  sched_yield()  unnecessarily  or  inappropriately  (e.g., when re‐
45       sources needed by other schedulable  threads  are  still  held  by  the
46       caller),  since  doing  so will result in unnecessary context switches,
47       which will degrade system performance.
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49       sched_yield() is intended for use with  real-time  scheduling  policies
50       (i.e., SCHED_FIFO or SCHED_RR).  Use of sched_yield() with nondetermin‐
51       istic scheduling policies such as SCHED_OTHER is unspecified  and  very
52       likely means your application design is broken.
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