Index for Section 2

Alphabetical listing for C

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
      These 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.

      There are no arguments.

  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.

      There are no arguments.

  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_& (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_& (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.

      There are no arguments.

  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.  The classcntl function returns -1 upon failure 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.

SEE ALSO
  class_scheduling(4), runclass(1), class_admin(8)