Changes the scheduling policy attribute of the specified thread
    attributes object.

1  –  C Binding

    #include <pthread.h>

    int
    pthread_attr_setschedpolicy (
             pthread_attr_t   *attr,
             int   policy);

2  –  Arguments

 attr

    Thread attributes object to be modified.

 policy

    New value for the scheduling policy attribute. Valid values are
    as follows:

       SCHED_BG_NP
       SCHED_FG_NP (also known as SCHED_OTHER)
       SCHED_FIFO
       SCHED_RR

    SCHED_OTHER is the default value.

3  –  Description

    This routine sets the scheduling policy of a thread that is
    created using the attributes object specified by the attr
    argument. The default value of the scheduling attribute is SCHED_
    OTHER.

    By default, a created thread inherits the policy of the thread
    calling pthread_create(). To specify a policy using this routine,
    scheduling inheritance must be disabled at the time the thread
    is created. Before calling pthread_create(), call pthread_attr_
    setinheritsched() and specify the value PTHREAD_EXPLICIT_SCHED
    for the inherit argument.

    Preemption is caused by both scheduling and policy. Never attempt
    to use scheduling as a mechanism for synchronization.

4  –  Return Values

    If an error condition occurs, this routine returns an integer
    value indicating the type of error. Possible return values are as
    follows:

    Return      Description

    0           Successful completion.
    [EINVAL]    The value specified by attr is not a valid thread
                attributes object, or the value specified by policy
                is invalid.

5  –  Associated Routines

       pthread_attr_init()
       pthread_attr_getschedpolicy()
       pthread_attr_setinheritsched()
       pthread_attr_setschedparam()
       pthread_create()