Initial trigger for system paging to begin. When this threshold is crossed, the page scanner wakes up to begin looking for memory pages to reclaim.

Unsigned long

The greater of 1/64th of physical memory or 512 Kbytes

The minimum value is 512 Kbytes or 1/64th of physical memory, whichever is greater, expressed as pages using the page size returned by getpagesize(3C).

The maximum is the number of physical memory pages. The maximum value should be no more than 30% of physical memory. The system does no enforcement of this range other than that described in the Validation section.

Pages

Yes, but dynamic changes are lost if a memory based DR operation occurs.

If lotsfree is greater than the amount of physical memory, the value is reset to the default.

The relationship of lotsfree is greater than desfree, which is greater than minfree, should be maintained at all times.

When demand for pages is subject to sudden sharp spikes, the memory algorithm might not be able to keep up with demand. One way to work around this problem is to start reclaiming memory at an earlier time. This solution gives the paging system some additional margin.

A rule of thumb is to set this parameter to 2 times what the system needs to allocate in a few seconds. This parameter is workload dependent: a DBMS server can probably work fine with the default settings, but a system doing heavy file system I/O might need to adjust this parameter.

For systems with relatively static workloads and large amounts of memory, adjust this value downwards. The minimum acceptable value is 512 Kbytes expressed as pages using the page size returned by getpagesize(3C).

Unstable

Amount of memory desired to be free at all times on the system.

Unsigned integer

lotsfree / 2

The minimum value is 256 Kbytes or 1/128th of physical memory, whichever is greater, expressed as pages using the page size returned by getpagesize(3C).

The maximum is the number of physical memory pages. The maximum value should be no more than 15% of physical memory. The system does no enforcement of this range other than that described in the Validation section.

Pages

Yes, unless dynamic reconfiguration operations that add or delete memory occur. At that point, the value is reset to whatever was provided in the /etc/system file or was calculated from the new physical memory value.

If desfree is greater than lotsfree, desfree is set to lotsfree / 2. No message is displayed.

The relationship of lotsfree is greater than desfree, which is greater than minfree, should be maintained at all times.

Several side effects can arise from increasing the value of this variable. When the new value nears or exceeds the amount of available memory on the system:

• Asynchronous I/O requests are not processed unless available memory exceeds desfree. Increasing the value of desfree can result in rejection of requests that otherwise would succeed.

• NFS Version 3 asynchronous writes are executed as synchronous writes.

• The swapper is awakened earlier, and the behavior of the swapper is biased towards more aggressive actions.

• The system might not prefault as many executable pages into the system. This side effect results in applications potentially running slower than they otherwise would.

For systems with relatively static workloads and large amounts of memory, adjust this value downwards. The minimum acceptable value is 256 Kbytes expressed as pages using the page size returned by getpagesize(3C).

Unstable

Minimum acceptable memory level. When memory drops below this number, the system biases allocations toward those necessary to successfully complete pageout operations or to swap processes completely out of memory, and either denies or blocks other allocation requests.

Unsigned integer

desfree / 2

The minimum value is 128 kbytes or 1/256th of physical memory, whichever is greater, expressed as pages using the page size returned by getpagesize(3C).

The maximum is the number of physical memory pages. The maximum value should be no more than 7.5% of physical memory. The system does no enforcement of this range other than that described in the Validation section.

Pages

Yes, unless dynamic reconfiguration operations that add or delete memory occur. At that point, the value is reset to whatever was provided in the /etc/system file or was calculated from the new physical memory value.

If minfree is greater than desfree, minfree is set to desfree / 2. No message is displayed.

The relationship of lotsfree is greater than desfree, which is greater than minfree, should be maintained at all times.

The default value is generally adequate. For systems with relatively static workloads and large amounts of memory, adjust this value downwards. The minimum acceptable value is 128 Kbytes expressed as pages using the page size returned by getpagesize(3C).

Unstable

Memory level at which blocking memory allocation requests are put to sleep, even if the memory is sufficient to satisfy the request.

Unsigned integer

minfree

The minimum value is 128 Kbytes or 1/256th of physical memory, whichever is greater, expressed as pages using the page size returned by getpagesize(3C).

The maximum is the number of physical memory pages. The maximum value should be no more than 4% of physical memory. The system does no enforcement of this range other than that described in the Validation section.

Pages

Yes, unless dynamic reconfiguration operations that add or delete memory occur. At that point, the value is reset to whatever was provided in the /etc/system file or was calculated from the new physical memory value.

If throttlefree is greater than desfree, throttlefree is set to minfree. No message is displayed.

The relationship of lotsfree is greater than desfree, which is greater than minfree, should be maintained at all times.

The default value is generally adequate. For systems with relatively static workloads and large amounts of memory, adjust this value downwards. The minimum acceptable value is 128 Kbytes expressed as pages using the page size returned by getpagesize(3C).

Unstable