sched_getscheduler(2) [freebsd man page]

SCHED_SETSCHEDULER(2)					      BSD System Calls Manual					     SCHED_SETSCHEDULER(2)

NAME

     sched_setscheduler, sched_getscheduler -- set/get scheduling policy and scheduler parameters

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sched.h>

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

     int
     sched_getscheduler(pid_t pid);

DESCRIPTION

     The sched_setscheduler() system call sets the scheduling policy and scheduling parameters of the process specified by pid to policy and the
     parameters specified in the sched_param structure pointed to by param, respectively.  The value of the sched_priority member in the param
     structure must be any integer within the inclusive priority range for the scheduling policy specified by policy.

     In this implementation, if the value of pid is negative the system call will fail.

     If a process specified by pid exists and if the calling process has permission, the scheduling policy and scheduling parameters will be set
     for the process whose process ID is equal to pid.

     If pid is zero, the scheduling policy and scheduling parameters are set for the calling process.

     In this implementation, the policy of when a process can affect the scheduling parameters of another process is specified in IEEE Std
     1003.1b-1993 (``POSIX.1'') as a write-style operation.

     The scheduling policies are in <sched.h>:

     [SCHED_FIFO]   First-in-first-out fixed priority scheduling with no round robin scheduling;

     [SCHED_OTHER]  The standard time sharing scheduler;

     [SCHED_RR]     Round-robin scheduling across same priority processes.

     The sched_param structure is defined in <sched.h>:

	   struct sched_param {
		   int sched_priority;	   /* scheduling priority */
	   };

     The sched_getscheduler() system call returns the scheduling policy of the process specified by pid.

     If a process specified by pid exists and if the calling process has permission, the scheduling parameters for the process whose process ID is
     equal to pid are returned.

     In this implementation, the policy of when a process can obtain the scheduling parameters of another process are detailed in IEEE Std
     1003.1b-1993 (``POSIX.1'') as a read-style operation.

     If pid is zero, the scheduling parameters for the calling process will be returned.  In this implementation, the sched_getscheduler system
     call will fail if pid is negative.

RETURN VALUES

     Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the
     error.

ERRORS

     On failure errno will be set to the corresponding value:

     [ENOSYS]		The system is not configured to support this functionality.

     [EPERM]		The requesting process doesn not have permission as detailed in IEEE Std 1003.1b-1993 (``POSIX.1'').

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

     [EINVAL]		The value of the policy argument is invalid, or one or more of the parameters contained in param is outside the valid
			range for the specified scheduling policy.

SEE ALSO

     sched_get_priority_max(2), sched_get_priority_min(2), sched_getparam(2), sched_rr_get_interval(2), sched_setparam(2), sched_yield(2)

STANDARDS

     The sched_setscheduler() and sched_getscheduler() system calls conform to IEEE Std 1003.1b-1993 (``POSIX.1'').

BSD
								  March 12, 1998							       BSD

sched_setscheduler(3C)					   Standard C Library Functions 				    sched_setscheduler(3C)

NAME

       sched_setscheduler - set scheduling policy and scheduling parameters

SYNOPSIS

       #include <sched.h>

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

DESCRIPTION

       The  sched_setscheduler()  function  sets the scheduling policy and scheduling parameters of the process specified by pid to policy and the
       parameters specified in the sched_param structure pointed to by param,  respectively.  The  value  of  the  sched_priority  member  in  the
       sched_param structure is any integer within the inclusive priority range for the scheduling policy specified by policy. The sched_setsched-
       uler() function ignores the other members  of  the  sched_param	structure.  If	the  value  of	pid  is  negative,  the  behavior  of  the
       sched_setscheduler() function is unspecified.

       The possible values for the policy parameter are defined in the header <sched.h> (see sched.h(3HEAD)):

       If a process specified by pid exists and if the calling process has permission, the scheduling policy and scheduling parameters are set for
       the process whose process  ID is equal to pid. The real or effective user  ID of the calling process must match the  real  or  saved  (from
       exec(2)) user  ID of the target process unless the effective user  ID of the calling process is 0. See Intro(2).

       If pid is 0, the scheduling policy and scheduling parameters are set for the calling process.

       To  change  the policy of any process to either of the real time policies  SCHED_FIFO or SCHED_RR, the calling process must either have the
       SCHED_FIFO or SCHED_RR policy or have an effective user ID of 0.

       The sched_setscheduler() function is considered successful if it succeeds in setting the scheduling policy and scheduling parameters of the
       process specified by pid to the values specified by policy and the structure pointed to by param, respectively.

RETURN VALUES

       Upon  successful  completion, the function returns the former scheduling policy of the specified process. If the sched_setscheduler() func-
       tion fails to complete successfully, the policy and scheduling paramenters remain unchanged, and the function returns -1 and sets errno	to
       indicate the error.

ERRORS

       The sched_setscheduler() function will fail if:

       EINVAL	 The  value of policy is invalid, or one or more of the parameters contained in param is outside the valid range for the specified
		 scheduling policy.

       EPERM	 The requesting process does not have permission to set either or both of the scheduling parameters or the  scheduling	policy	of
		 the specified process.

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

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Committed 		   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+
       |Standard		     |See standards(5). 	   |
       +-----------------------------+-----------------------------+

SEE ALSO

       priocntl(1),  Intro(2),	exec(2), priocntl(2), librt(3LIB), sched.h(3HEAD), sched_get_priority_max(3C), sched_getparam(3C), sched_getsched-
       uler(3C), sched_setparam(3C), attributes(5), standards(5)

SunOS 5.11							    1 Apr 2008						    sched_setscheduler(3C)