unlockable_mem

Specify minimum amount of memory that is to remain reserved for system overhead and virtual memory management use.

Acceptable Values:

Minimum

0

Maximum

Available memory indicated at power-up

Default

0 (system sets to appropriate value)

Specify integer value. For more information, see Specifying Parameter Values.

Description

unlockable_mem defines the minimum amount of memory that is to always remain available for virtual memory management and system overhead. Increasing the amount of unlockable memory decreases the amount of lockable memory because:

• Total available system memory minus unlockable_mem = lockable memory

Specify unlockable_mem in 4-Kbyte pages. Note that current amounts of available and lockable memory are listed along with the physical page size in startup messages, which you can view later by running /etc/dmesg.

If the value for unlockable_mem exceeds available system memory, it is set equal to available memory (reducing lockable memory to zero).

Any call that requires lockable memory may fail if the amount of lockable memory is insufficient. Note that lockable memory is available for virtual memory except when it is locked.

Lockable memory is used for:

• Process images and overhead locked using the plock() system call (see HP-UX Reference entry plock(2)).

• Shared memory segments locked with the SHM_LOC command of the shmctl() system call (see HP-UX Reference entry shmctl(2)).

• Miscellaneous dynamic kernel data structures used by the shared memory system and some drivers.

Related Parameters

unlockable_mem must always be less than the total amount of available memory in the system.

Additional Information

• Overview of Miscellaneous Parameters
• List of parameters
• Browse configurable kernel parameters help