Swapping-Related Parameters
Swapping in the Solaris OS is accomplished by the swapfs pseudo file system.
The combination of space on swap devices and physical memory is treated as
the pool of space available to support the system for maintaining backing store
for anonymous memory. The system attempts to allocate space from disk devices first,
and then uses physical memory as backing store. When swapfs is forced to
use system memory for backing store, limits are enforced to ensure that the
system does not deadlock because of excessive consumption by swapfs.
swapfs_reserve
- Description
Defines the amount of system memory that is reserved for use by system (UID = 0) processes.
- Data Type
Unsigned long
- Default
The smaller of 4 Mbytes and 1/16th of physical memory
- Range
The minimum value is 4 Mbytes or 1/16th of physical memory, whichever is smaller, expressed as pages using the page size returned by getpagesize.
The maximum value is the number of physical memory pages. The maximum value should be no more than 10 percent of physical memory. The system does not enforce this range, other than that described in the Validation section.
- Units
Pages
- Dynamic?
No
- Validation
None
- When to Change
Generally not necessary. Only change when recommended by a software provider, or when system processes are terminating because of an inability to obtain swap space. A much better solution is to add physical memory or additional swap devices to the system.
- Commitment Level
Unstable
swapfs_minfree
- Description
Defines the desired amount of physical memory to be kept free for the rest of the system. Attempts to reserve memory for use as swap space by any process that causes the system's perception of available memory to fall below this value are rejected. Pages reserved in this manner can only be used for locked-down allocations by the kernel or by user-level processes.
- Data Type
Unsigned long
- Default
The larger of 2 Mbytes and 1/8th of physical memory
- Range
1 to amount of physical memory
- Units
Pages
- Dynamic?
No
- Validation
None
- When to Change
When processes are failing because of an inability to obtain swap space, yet the system has memory available.
- Commitment Level
Unstable