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occasional core dump
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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)
