semsys:seminfo_semmsl
| Description | Maximum number of System
V semaphores per semaphore identifier.
| | Data Type | Signed integer
| | Default | 25
| | Range | 1 to MAXINT
| | Dynamic? | No
| | Validation | The amount of space that
could possibly be consumed by the semaphores and their supporting data structures
is compared to 25% of the kernel memory available at the time the module is
first loaded. If the memory threshold is exceeded, the module refuses to load
and the semaphore facility is not available.
| | When to Change | When the default
value is not enough. Generally changed at the recommendation of software vendors.
No error messages are displayed when an attempt is made to create more semaphores
in a set than are currently configured. The application sees a return code
of EINVAL from a semget(2) call.
| | Commitment Level | Unstable
|
semsys:seminfo_semopm
| Description | Maximum number of System
V semaphore operations per semop(2) call. This parameter refers to the number
of sembufs in the sops array that is
provided to the semop() system call.
| | Data Type | Signed integer
| | Default | 10
| | Range | 1 to MAXINT
| | Dynamic? | No
| | Validation | The amount of space that
could possibly be consumed by the semaphores and their supporting data structures
is compared to 25% of the kernel memory available at the time the module is
first loaded. If the memory threshold is exceeded, the module refuses to load
and the semaphore facility is not available.
| | When to Change | When the default
value is not enough. Generally changed at the recommendation of software vendors.
No error messages are displayed when an attempt is made to perform more semaphore
operations in a single semop call than are currently allowed.
The application sees a return code of E2BIG from a semop() call.
| | Commitment Level | Unstable
|
semsys:seminfo_semmnu
| Description | Total number of undo
structures supported by the System V semaphore system.
| | Data Type | Signed integer
| | Default | 30
| | Range | 1 to MAXINT
| | Dynamic? | No
| | Validation | The amount of space that
could possibly be consumed by the semaphores and their supporting data structures
is compared to 25% of the kernel memory available at the time the module is
first loaded. If the memory threshold is exceeded, the module refuses to load
and the semaphore facility is not available.
| | When to Change | When the default
value is not enough. Generally changed at the recommendation of software vendors.
No error message is displayed when an attempt is made to perform more undo
operations than are currently configured. The application sees a return value
of ENOSPC from a semop(2) call when the system runs out of undo
structures.
| | Commitment Level | Unstable
| | Changes From Previous Release | For
information, see semsys:seminfo_semmnu.
|
semsys:seminfo_semume
| Description | Maximum number of System
V semaphore undo structures that can be used by any one process.
| | Data Type | Signed integer
| | Default | 10
| | Range | 1 to MAXINT
| | Dynamic? | No
| | Validation | The amount of space that
could possibly be consumed by the semaphores and their supporting data structures
is compared to 25% of the kernel memory available at the time the module is
first loaded. If the memory threshold is exceeded, the module refuses to load
and the semaphore facility is not available.
| | When to Change | When the default
value is not enough. Generally changed at the recommendation of software vendors.
No error messages are displayed when an attempt is made to perform more undo
operations than are currently configured. The application sees a return code
of EINVAL from a semop(2) call.
| | Commitment Level | Unstable
|
semsys:seminfo_semaem
| Description | Maximum value that a
semaphore's value in an undo structure can be set to.
| | Data Type | Unsigned short
| | Default | 16,384
| | Range | 1 to 65,535
| | Dynamic? | No
| | Validation | None
| | When to Change | When the default
value is not enough. Generally changed at the recommendation of software vendors.
No error messages are displayed when an attempt is made to perform more undo
operations than are currently configured. The application sees a return code
of EINVAL from a semop(2) call.
| | Commitment Level | Unstable
|
System V Shared Memory
System V shared memory allows the creation of a segment by a process.
Cooperating processes can attach to the memory segment (subject to access
permissions on the segment) and gain access to the data contained in the segment.
This capability is implemented as a loadable module. Entries in the /etc/system file must contain the shmsys: prefix.
Starting with the Solaris 7 release, the keyserv daemon
uses System V shared memory.
A special kind of shared memory known as intimate shared memory (ISM)
is used by DBMS vendors to maximize performance. When a shared memory segment
is made into an ISM segment, the memory for the segment is locked. This enables
a faster I/O path to be followed and improves memory usage because a number
of kernel resources describing the segment are now shared between all processes
attaching to the segment in ISM mode.
The module is dynamically loaded on first reference. Parameters provided
to the subsystem are validated at that time.
This facility is different from the POSIX 1003.1b shared memory facility.
shmsys:shminfo_shmmax
| Description | Maximum size of system
V shared memory segment that can be created. This parameter is an upper limit
that is checked before the application sees if it actually has the physical
resources to create the requested memory segment.
Attempts to create a shared memory section whose size is zero or whose
size is larger than the specified value will fail with an EINVAL error.
This parameter specifies only the largest value the operating system
can accept for the size of a shared memory segment. Whether the segment can
be created depends entirely on the amount of swap space available on the system
and, for a 32-bit process, whether there is enough space available in the
process's address space for the segment to be attached.
| | Data Type | Unsigned long
| | Default | 8,388,608
| | Range | 0 - MAXUINT32 on 32-bit systems,
0 - MAXUINT64 on 64-bit systems
| | Units | Bytes
| | Dynamic? | No. Loaded into shmmax field of shminfo structure.
| | Validation | None
| | When to Change | When the default
value is too low. Generally changed at the recommendation of software vendors,
but unless the size of a shared memory segment needs to be constrained, setting
this parameter to the maximum possible value has no side effects.
| | Commitment Level | Unstable
| | Change History | For information,
see shmsys:shminfo_shmmax (Solaris 9 12/02).
|
|
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