Package oshi.hardware

Interface VirtualMemory

All Known Implementing Classes:

AbstractVirtualMemory

@ThreadSafe
public interface VirtualMemory

The VirtuallMemory class tracks information about the use of a computer's virtual memory (swap file) which temporarily moves rarely accessed information to a disk or other storage device.

Method Summary

Modifier and Type	Method	Description
long	getSwapPagesIn()	Number of pages read from paging/swap file(s) to resolve hard page faults.
long	getSwapPagesOut()	Number of pages written to paging/swap file(s) to free up space in physical memory.
long	getSwapTotal()	The current size of the paging/swap file(s), in bytes.
long	getSwapUsed()	The current memory committed to the paging/swap file(s), in bytes
long	getVirtualInUse()	The memory currently committed by the system, in bytes.
long	getVirtualMax()	The maximum memory that can be committed by the system without extending the paging file(s), in bytes.

Method Details

getSwapTotal

long getSwapTotal()

The current size of the paging/swap file(s), in bytes. If the paging/swap file can be extended, this is a soft limit.

Returns:

Total swap in bytes.

getSwapUsed

long getSwapUsed()

The current memory committed to the paging/swap file(s), in bytes

Returns:

Swap used in bytes

getVirtualMax

long getVirtualMax()

The maximum memory that can be committed by the system without extending the paging file(s), in bytes. Also called the Commit Limit. If the paging/swap file can be extended, this is a soft limit. This is generally equal to the sum of the sizes of physical memory and paging/swap file(s).

On Linux, represents the total amount of memory currently available to be allocated on the system based on the overcommit ratio, identified as CommitLimit. This may be higher or lower than the total size of physical and swap memory depending on system configuration.

Returns:

Max Virtual Memory in bytes

getVirtualInUse

long getVirtualInUse()

The memory currently committed by the system, in bytes. Also called the Commit Total. This is generally equal to the sum of the bytes used of physical memory and paging/swap file(s).

On Windows, committing pages changes this value immediately; however, the physical memory is not charged until the pages are accessed, so this value may exceed the sum of used physical and paging/swap file memory.

Returns:

Swap used in bytes

getSwapPagesIn

long getSwapPagesIn()

Number of pages read from paging/swap file(s) to resolve hard page faults. (Hard page faults occur when a process requires code or data that is not in its working set or elsewhere in physical memory, and must be retrieved from disk.) This property was designed as a primary indicator of the kinds of faults that cause system-wide delays. It includes pages retrieved to satisfy faults in the file system cache (usually requested by applications) and in non-cached mapped memory files.

Returns:

Pages swapped in

getSwapPagesOut

long getSwapPagesOut()

Number of pages written to paging/swap file(s) to free up space in physical memory. Pages are written back to disk only if they are changed in physical memory, so they are likely to hold data, not code. A high rate of pages output might indicate a memory shortage. The operating system writes more pages back to disk to free up space when physical memory is in short supply.

Returns:

Pages swapped out