thread

    Thread whose scheduling policy and parameters are to be changed.

 policy

    New scheduling policy value for the thread specified in thread.
    The following are valid values:

       SCHED_BG_NP
       SCHED_FG_NP
       SCHED_FIFO
       SCHED_OTHER
       SCHED_RR

 param

    New values of the scheduling parameters associated with the
    scheduling policy for the thread specified in thread. Valid
    values for the sched_priority field of a sched_param structure
    depend on the chosen scheduling policy. Use the POSIX routines
    sched_get_priority_min() or sched_get_priority_max()  to
    determine the low and high limits of each policy.

    Additionally, the Threads Librray provides nonportable priority
    range constants, as follows:

    Low              High

    PRI_FIFO_MIN     PRI_FIFO_MAX
    PRI_RR_MIN       PRI_RR_MAX
    PRI_OTHER_MIN    PRI_OTHER_MAX
    PRI_FG_MIN_NP    PRI_FG_MAX_NP
    PRI_BG_MIN_NP    PRI_BG_MAX_NP

    The default priority varies by platform. On Tru64 UNIX, the
    default is 19 (that is, the POSIX priority of a normal timeshare
    process). On other platforms the default priority is the midpoint
    between PRI_FG_MIN_NP and PRI_FG_MAX_NP.