oshi.hardware.VirtualMemory Maven / Gradle / Ivy
/*
* Copyright 2019-2022 The OSHI Project Contributors
* SPDX-License-Identifier: MIT
*/
package oshi.hardware;
import oshi.annotation.concurrent.ThreadSafe;
/**
* 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.
*/
@ThreadSafe
public interface VirtualMemory {
/**
* The current size of the paging/swap file(s), in bytes. If the paging/swap file can be extended, this is a soft
* limit.
*
* @return Total swap in bytes.
*/
long getSwapTotal();
/**
* The current memory committed to the paging/swap file(s), in bytes
*
* @return Swap used in bytes
*/
long getSwapUsed();
/**
* 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 {@code CommitLimit}. This may be higher or lower than the total size of physical
* and swap memory depending on system configuration.
*
* @return Max Virtual Memory in bytes
*/
long getVirtualMax();
/**
* 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.
*
* @return Swap used in bytes
*/
long getVirtualInUse();
/**
* 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.
*
* @return Pages swapped in
*/
long getSwapPagesIn();
/**
* 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.
*
* @return Pages swapped out
*/
long getSwapPagesOut();
}