sched_setparam(3)					     Library Functions Manual						 sched_setparam(3)

NAME

       sched_setparam - Sets the scheduling parameters of the specified process (P1003.1b)

LIBRARY

       Realtime Library (librt.so, librt.a)

SYNOPSIS

       #include <sched.h>

       int sched_setparam (
       pid_t pid,
       const struct sched_param *param);

PARAMETERS

       pid     Specifies  the  ID  of  the  process  whose scheduling parameters are set. If pid is zero, the scheduling parameters of the calling
	       process are set.

       *param  Specifies a pointer to a sched_param structure, which contains the scheduling parameters of the specified process.  Currently,  the
	       sched_param structure contains only a priority field.  The value of the priority value is any integer within the priority range for
	       the current scheduling policy of the process specified by pid.

DESCRIPTION

       The sched_setparam function changes the scheduling parameters of a process. Setting priorities such that the most critical process has  the
       highest priority allows applications to determine more effectively when a process will run.

       At  run	time,  a process starts out with an initial priority of SCHED_PRIO_USER_MAX. A call to the sched_setparam function that raises the
       priority of a process also raises the maximum priority for the process. This higher maximum priority exists for the life of the process	or
       until  the  priority  is  set to a new, higher priority through another call to the sched_setparam function. The maximum priority cannot be
       adjusted downward, but subsequent calls to the sched_setparam or sched_setscheduler functions can specify that a process  run  at  a  lower
       priority.

       You  must have superuser privileges to set the priority above the user maximum, SCHED_PRIO_USER_MAX.  A superuser can set the priority out-
       side the range of the specified pid's scheduling policy.

       When the function completes, the target process resumes execution after all other runnable processes  of  equal	or  greater  priority  are
       scheduled to run.  If the priority of the target process is set higher than that of the calling process, and if the target process is ready
       to run, then the target process will preempt the calling process. If the calling process  set  its  own	priority  lower  than  some  other
       process,  then  the other process will preempt the calling process. In either situation, the calling process might not receive notification
       of the completion of the requested priority change until the target process has executed.

       The scheduling parameters of the process as indicated by pid are obtained with a call to the sched_getparam function.

       The priority of a process is inherited across fork and exec calls.

RETURN VALUES

       On a successful call to the sched_setparam function, the scheduling parameters are set and a value of 0 (zero) is returned.  On	an  unsuc-
       cessful call, a value of -1 is returned and errno is set to indicate that an error occurred and the priority is unchanged.

ERRORS

       The sched_setparam function fails under the following conditions:

       [EINVAL]       One  or  more of the requested scheduling parameters is outside the range defined for the specified pid's scheduling policy.
		      This error does not apply for superusers.

       [EPERM]	      The requesting process does not have permission to set the scheduling parameters for the specified process, nor does it have
		      appropriate privilege to invoke the sched_setparam function.

       [ESRCH]	      No process can be found corresponding to that specified by pid.

RELATED INFORMATION

       Functions: getpid(2), sched_getparam(3), sched_getscheduler(3), sched_setscheduler(3)

       Guide to Realtime Programming delim off

																 sched_setparam(3)