sched_yield - yield the processor
#include <sched.h>
int sched_yield(void);
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.
On success,
sched_yield() returns 0. On error, -1 is returned, and
errno is set appropriately.
In the Linux implementation,
sched_yield() always succeeds.
POSIX.1-2001, POSIX.1-2008.
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.
sched_yield() is intended for use with real-time scheduling policies
(i.e.,
SCHED_FIFO or
SCHED_RR). Use of
sched_yield() with
nondeterministic scheduling policies such as
SCHED_OTHER is unspecified
and very likely means your application design is broken.
sched(7)