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classcntl(2)
NAME
  classcntl - manage kernel class scheduling properties.

SYNOPSIS
  #include <sys/types.h>
  #include <sys/class.h>

  int classcntl (
	 int opcode,
	 int	 arg1,
	 int	 arg2,
	 int	 arg3);

PARAMETERS
  opcode
      Identifies the type of operation (see below).

  arg1, arg2, and arg3
      are opcode dependent and are described below.

DESCRIPTION
  The classcntl function is used to control kernel class scheduler functions.

  Opcode and Argument Descriptions

  CL_OP_ENABLE
	    Informs the kernel that class scheduling is turned on.  The
	    kernel will look for threads being class scheduled and charge
	    time used against the class.  Once class scheduling has been
	    enabled, it is necessary to tell the kernel which class members
	    to begin charging via the CL_OP_ADD_TO_CLASS opcode.

  arguments none.

  CL_OP_DISABLE
	    Turn off class scheduling.	All class members are reset to their
	    original state.  If the kernel has been notified, via
	    CL_OP_DAEMON_ALIVE, that a class scheduler daemon has been
	    started, that daemon will be terminated.

  arguments none.

  CL_OP_GET_CLASS_LIST
	    Gets the class_list array from the kernel.	The class_list array
	    is a list of MAX_NUM_CLASSES integers.

  arguments
	    arg1    User buffer into which the kernel data is copied.
	    arg2    Number of bytes to copy.
	    arg3    Unused.

  CL_OP_ADD_TO_CLASS
	    Identify class members to the kernel so that their CPU usage is
	    charged to their class.

  arguments
	    arg1    Class type, as in CL_TYPE_XXX (see class.h).
	    arg2    Numeric value for member (gid, uid,
		    session id, pgrp id, or pid).
	    arg3    Index into the class_list array that
		    represents the class.

  CL_OP_DEL_FROM_CLASS
	    Notify the kernel that a class member's CPU time is not to be
	    charged.

  arguments
	    arg1    Type as in CL_TYPE_XXX (see class.h).
	    arg2    Numeric value for member (gid, uid,
		    session id, pgrp id, or pid).
	    arg3    Unused.

  CL_OP_SET_CLASS_LIST
	    Sets the class_list array into the kernel.	The class_list array
	    is a list of MAX_NUM_CLASSES integers.

  arguments
	    arg1    User buffer into which is copied into the kernel.
	    arg2    Number of bytes to copy.
	    arg3    idle_enforce -  when set to 0, a class is allowed
			    to exceed its CPU percentage if the system
			    would be otherwise idle.  Else, a class is
			    forced to its CPU percentage even if the
			    system has no other work.

  CL_OP_DAEMON_ALIVE
	    Informs the kernel that a class_scheduler daemon is running and
	    how often it checks class CPU usage.  Should the daemon fail to
	    run in twice the interval specified, the kernel will disable
	    class scheduling.

  arguments
	    arg1    The pid of the daemon.
	    arg2    The interval, in seconds.
	    arg3    Unused.

  CL_OP_IS_ENABLED
	    Returns 1 if class scheduling is currently enabled, 0 otherwise.

  arguments none

  CL_OP_GET_PID_CLASS
	    Get the class index of a specified process id (pid).

  arguments
	    arg1    Pid of the target process.
	    arg2    Address of the user data (integer) to receive
		    the class index.
	    arg3    Unused

RESTRICTIONS
  The caller must have root access rights.


RETURN VALUES
  Unless otherwise noted above, the classcntl returns a value of zero (0) on
  success.  Upon failure, the classcntl function returns -1 and sets errno to
  indicate the error.

ERRORS
  The classcntl function fails under the following conditions:

  [EPERM]   The Caller does not have super user privileges.

  [EACCESS] Access denied - class scheduling not enabled.

RELATED INFORMATION
  class_scheduling(4), runclass(1),  class_admin(8).