How do I adjust interprocess communications (IPC) variables?

Processes can communicate with each other by using one of several types of interprocess communication (IPC). IPC allows information transfer or synchronization to occur between processes.

Prior to the Solaris 10 release, IPC tunable parameters were set by adding an entry to the /etc/system file. The resource controls facility now provides resource controls that define the behavior of the kernel's IPC facilities. These resource controls replace the /etc/system tunables.

Solaris 2.6 / 7 / 8 / 9

All changes are made in /etc/system

Message Queue

OptionDescriptionDefaults
msgsys:msginfo_msgmap Number of entries in the message map 100
msgsys:msginfo_msgmax Maximum message size 2048
msgsys:msginfo_msgmnb Maximum bytes in queue 4096
msgsys:msginfo_msgmni Number of message queue identifiers 50
msgsys:msginfo_msgssz Message segment size 8
msgsys:msginfo_msgtql Number of system message headers 40
msgsys:msginfo_msgseg Number of message segments 1024
Must be less than 32768

Semaphores

OptionDescriptionDefaults
semsys:seminfo_semmap Number of entries in the semaphore map 10
semsys:seminfo_semmni Number of identifiers 10
semsys:seminfo_semmns Number of semaphores in the system 60
semsys:seminfo_semmnu Number of processes in the undo facility 30
semsys:seminfo_semmsl Maximum semaphores per id 25
semsys:seminfo_semopm Maximum operations per call 10
semsys:seminfo_semume Number of undo structures per process 10

Shared Memory

OptionDescriptionDefaults
shmsys:shminfo_shmmax Maximum size of a shared memory segment. Solaris 2.6 / 7 / 8
1,048,576
Solaris 9
8,388,608
shmsys:shminfo_shmmin Minimum size of a shared memory segment.
Changing this value is not recommended as high values can cause application failure
1
shmsys:shminfo_shmmni Maximum number of total shared memory segments that can be created 100
shmsys:shminfo_shmseg Maximum number of shared memory segments per process 6

Solaris 10

New project facility. In addition to global settings, as in prior Solaris releases, it can also handle configuration per project, and per process. Controls are also now available while system is running.

The examples that follow make the necessary changes dymanically.

Message Queue

OptionDescriptionDefaultsMaximums
project.max-msg-ids
Replaces msgsys:msginfo_msgmni
Maximum number of message queue ids 128 16777216 (2^24)
Example: prctl -n project.max-msg-ids -r -v 1024 -i project 3
project.max-msg-qbytes Replaces msgsys:msginfo_msgmnb
Maximum number of bytes of messages on a queue
65536 32-bit 4294967295(ULONG_MAX, 32-bit)
64-bit 18446744073709551615 (ULONG_MAX, 64-bit)
Example: prctl -n project.max-msg-qbytes -r -v 1024 -i project 3
project.max-msg-messages
Replaces msgsys:msginfo_msgtql
Maximum number of messages in queue 8192 4294967295 (UINT_MAX)
Example: prctl -n project.max-msg-messages -r -v 16384 -i project 3

Semaphore

OptionDescriptionDefaultsMaximums
project.max-sem-ids
Replaces semsys:seminfo_semmni
Maximum number of semaphore ids allowed 128 16777216 (2^24)
Example: prctl -n project.max-sem-ids -r -v 256 -i project 3
project.max-sem-nsems
Replaces semsys:seminfo_semmsi
Maximum number of semaphores per set 512 32767 (SHRT_MAX)
Example: prctl -n project.max-sem-nsems -r -v 1024 -i project 3
project.max-sem-ops
Replaces semsys:seminfo_semopm
Maximum number of semaphore operations allowed 512 2147483647 (INT_MAX)
Example: prctl -n project.max-sem-ops -r -v 1024 -i project 3

Shared Memory

OptionDescriptionDefaultsMaximums
project.max-shm-ids
Replaces shmsys:shminfo_shmmni
Maximum number of shared memory ids allowed a project. 128 16777216 (2^24)
Example: prctl -n project.max-shm-ids -r -v 256 -i project 3
project.max-shm-memory
Replaces shmsys:shminfo_shmmax
Total amount of shared memory allowed a project (not merely per segment, as in previous versions) 1/4 Memory 18446744073709551616 (UINT64_MAX)
Example: prctl -n project.max-shm-memory -r -v 4G -i project 3

To make the changes persistent under Solaris 10 either modify the /etc/project manually, or use the projmod command, for exmple if we want to set max-shm-memory to 4G we would run:

projmod -sK "project.max-shm-memory=(priv,4G,deny)" default