WebSphere® MQ makes use of System V IPC resources, in particular shared memory and semaphores. The default configuration of these resources, supplied with your installation, is probably adequate for WebSphere MQ but if you have a large number of queues or connected applications, you might need to increase this configuration.
/proc/sys/kernel/shmmax - The maximum size of a shared memory segment. /proc/sys/kernel/shmmni - The maximum number of shared memory segments. /proc/sys/kernel/shmall - The maximum amount of shared memory that can be allocated. /proc/sys/kernel/sem - The maximum number and size of semaphore sets that can be allocated.
cat /proc/sys/kernel/shmmaxTo change the maximum size of a shared memory segment to 256 MB enter:
echo 268435456 > /proc/sys/kernel/shmmax
cat /proc/sys/kernel/semThis returns 4 numbers indicating:
SEMMSL - The maximum number of semaphores in a sempahore set SEMMNS - The maximum number of sempahores in the system SEMOPM - The maximum number of operations in a single smeop call SEMMNI - The maximum number of sempahore sets
To configure these values every time the machine is restarted you are recommended to add these commands to a startup script in /etc/rc.d/...