sys_attrs_ipc(5)						File Formats Manual						  sys_attrs_ipc(5)

NAME

       sys_attrs_ipc - attributes for the ipc kernel subsystem

DESCRIPTION

       This reference page describes attributes for the Interprocess Communication (ipc) kernel subsystem.

       In the following list, attributes whose names are preceded by an asterisk (*) can be modified at run time as well as at boot time.

       See sys_attrs(5) for an introduction to system attributes and how to set them.

	      The maximum number of kernel IPC ports that can be used on the system at one time.

	      Default value: (task-max * 3 + thread_max) + (thread_max * 2) + 2000

	      (Values of variables used to establish default value: task_max = nproc +1; thread_max = nproc *2; nproc = 20 + 8 * maxusers)

	      Do not modify the default setting for this attribute unless instructed to do so by support personnel or by patch kit documentation.

	      Maximum size, in bytes, of a single System V message.

	      Default value: 8192 (bytes, which equal 1 page)

	      Minimum value: 0

	      Maximum value: INT_MAX

	      Values  for  this  attribute are restricted by the amount of main memory on the system. The minimum value (0) disables the messaging
	      system.

	      Maximum number of bytes that can be queued to a single System V message queue.

	      Default value: 16,384 (bytes, which equal 2 pages)

	      Minimum value: 0

	      Maximum value: INT_MAX

	      Values for this attribute are restricted by the amount of main memory on the system. The minimum value (0)  disables  the  messaging
	      system.

	      Maximum number of System V message queues that can be used on the system at one time.

	      Default value: 50 (queues) The system rounds the number to the value associated with the next higher power of two; for example, 64.

	      Minimum value: 0

	      Maximum value: INT_MAX

	      Values  for  this  attribute are restricted by the amount of main memory on the system. The minimum value (0) disables the messaging
	      system.

	      Maximum number of messages (system wide) that can be queued to System V message queues at one time.

	      Default value: 40 (messages)

	      Minimum value: 0

	      Maximum value: INT_MAX

	      Values for this attribute are restricted by the amount of main memory on the system. The minimum value (0)  disables  the  messaging
	      system.

	      A value that controls the maximum adjustment that can be made to any System V semaphore when a process exits.

	      Default value: 16,384

	      Minimum value: 0

	      Maximum value: 65,536

	      Maximum number of System V semaphores that can be used on the system at one time.

	      Default  value:  10  (semaphores) (The system rounds the number to the value associated with the next higher power of two; for exam-
	      ple, 16.)

	      Minimum value: 0

	      Maximum value: INT_MAX

	      Maximum number of System V semaphores that can be used by a single process at one time.

	      Default value: 25 (semaphores)

	      Minimum value: 0

	      Maximum value: INT_MAX

	      Maximum number of operations that can be outstanding on a single System V semaphore at one time.

	      Default value: 10 (operations)

	      Minimum value: 0

	      Maximum value: INT_MAX

	      Maximum number of undo operations that can be outstanding on a single System V semaphore at one time.

	      Default value: 10 (operations)

	      Minimum value: 0

	      Maximum value: INT_MAX

	      Maximum integer value that any System V semaphore can contain.

	      Default value: 32,767

	      Minimum value: 0

	      Maximum value: INT_MAX, but do not enter values higher than 65535

	      A value that sets default policy for shared memory allocation on NUMA-enabled systems (GS80, GS160, GS320). A value of 1 means  that
	      shared memory is striped across Resource Affinity Domains (RADs). A value of 0 means that shared memory is not striped across RADs.

	      Default value: 1, for NUMA-enabled systems; 0 for other systems.

	      Although	you  can change the value of this attribute while the system is running, there are currently no known situations for which
	      the shm_allocate_striped value should be changed. A value of 1 is the recommended default  policy  for  all  applications  on  NUMA-
	      enabled  systems. Furthermore, changing the value to 0 on these systems does not override use of striped memory allocation by appli-
	      cations that explicitly specify and control it through NUMA-specific programming interfaces. Changing the value to 1 on systems that
	      do not support NUMA has no effect. See numa_intro(3) for an introduction to NUMA.

	      Disables	(0)  or enables (1) the dumping of shared memory regions to the core file.  The attribute is only used in conjunction with
	      shared memory.

	      Default value: 1 (on).

	      Maximum size, in bytes, of a single System V shared memory region.

	      Default value: 4,194,304 (bytes) (This value equals 512 pages)

	      Minimum size, in bytes, of a single System V shared memory region.

	      Default value: 1 (All requests are rounded to the next page size.)

	      Maximum number of shared memory regions that can be used on the system at one time.

	      Default value: 100 (regions) (The system rounds the number to the value associated with the next higher power of two;  for  example,
	      128.)

	      Maximum number of System V shared memory regions that can be attached to a single process at one time.

	      Default value: 32 (regions)

	      If  enabled  (1),  writes segmented shared memory contents when an application issues a core dump. If disabled (0), segmented shared
	      memory is not written to the core dump.

	      Default value: 1 (enabled)

	      Because segmented shared memory can be  large, the amount of time needed to dump the region to a core file and the  amount  of  file
	      system space required by the operation can be extensive, especially in large database environments.  Therefore, although shared mem-
	      ory can be useful for debugging, you may not want to include it in core files because of time and resource limitations.

	      This attribute can be modified at run time.

	      The minimum size, in bytes, of a System V shared region for the use of shared page tables.  Setting this value to  0   disables  the
	      use  of  shared  page  tables  for shared memory. The size must be at least equal to the value of SSM_SIZE, which is  defined in the
	      machine/pmap.h file (the default is 8 MB).

	      This attribute can be modified at run time.

	      Default value: SSM_SIZE

	      Minimum value: SSM_SIZE

SEE ALSO

       sys_attrs(5)

       System Configuration and Tuning

																  sys_attrs_ipc(5)