C#调用API调整应用程序占用物理内存大小

.net应用程序启动后会占用大量物理内存,有些客户是不能容忍这样的情况发生，所以必要时要使用虚拟内存替代物理内存的使用。
引用
using System.Runtime.InteropServices;

具体方法：

        [DllImport("kernel32.dll")]
        private static extern bool SetProcessWorkingSetSize(
            IntPtr process,
            int minSize,
            int maxSize
            );

        private static void FlushMemory()
        {
            GC.Collect();
            GC.WaitForPendingFinalizers();
            if (Environment.OSVersion.Platform == PlatformID.Win32NT)
                SetProcessWorkingSetSize(System.Diagnostics.Process.GetCurrentProcess().Handle,20,20);
        }

process参数是进程句柄
minSize最小内存页
maxSize最大内存页

该方法执行后只调整一次内存占用，之后会继续占用物理内存，需要在大型内存操作后执行。
注：该方法会损失一定性能，如果对性能要求极高请放弃使用本方法。

SetProcessWorkingSetSize

The SetProcessWorkingSetSize function sets the minimum and maximum working set sizes for the specified process.

BOOL SetProcessWorkingSetSize(
HANDLE hProcess,
  SIZE_T dwMinimumWorkingSetSize,
  SIZE_T dwMaximumWorkingSetSize
);

Parameters

hProcess

[in] Handle to the process whose working set sizes is to be set.

The handle must have the PROCESS_SET_QUOTA access right. For more information, see Process Security and Access Rights.

dwMinimumWorkingSetSize

[in] Minimum working set size for the process, in bytes. The virtual memory manager attempts to keep at least this much memory resident in the process whenever the process is active.

This parameter must be greater than zero but less than or equal to the maximum working set size. The default size is 50 pages (for example, this is 204,800 bytes on systems with a 4K page size). If the value is greater than zero but less than 20 pages, the minimum value is set to 20 pages.

If both dwMinimumWorkingSetSize and dwMaximumWorkingSetSize have the value (SIZE_T)-1, the function temporarily trims the working set of the specified process to zero. This essentially swaps the process out of physical RAM memory.

dwMaximumWorkingSetSize

[in] Maximum working set size for the process, in bytes. The virtual memory manager attempts to keep no more than this much memory resident in the process whenever the process is active and available memory is low.

This parameter must be greater than or equal to 13 pages (for example, 53,248 on systems with a 4K page size), and less than the system-wide maximum (number of available pages minus 512 pages). The default size is 345 pages (for example, this is 1,413,120 bytes on systems with a 4K page size).

Return Values

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. Call GetLastError to obtain extended error information.

Remarks

The working set of a process is the set of memory pages currently visible to the process in physical RAM memory. These pages are resident and available for an application to use without triggering a page fault. The minimum and maximum working set sizes affect the virtual memory paging behavior of a process.

The working set of the specified process can be emptied by specifying the value (SIZE_T)-1 for both the minimum and maximum working set sizes.

If the values of either dwMinimumWorkingSetSize or dwMaximumWorkingSetSize are greater than the process' current working set sizes, the specified process must have the SE_INC_BASE_PRIORITY_NAME privilege. Users in the Administrators and Power Users groups generally have this privilege. For more information about security privileges, see Privileges.

The operating system allocates working set sizes on a first-come, first-served basis. For example, if an application successfully sets 40 megabytes as its minimum working set size on a 64-megabyte system, and a second application requests a 40-megabyte working set size, the operating system denies the second application's request.

Using the SetProcessWorkingSetSize function to set an application's minimum and maximum working set sizes does not guarantee that the requested memory will be reserved, or that it will remain resident at all times. When the application is idle, or a low-memory situation causes a demand for memory, the operating system can reduce the application's working set. An application can use the VirtualLock function to lock ranges of the application's virtual address space in memory; however, that can potentially degrade the performance of the system.

When you increase the working set size of an application, you are taking away physical memory from the rest of the system. This can degrade the performance of other applications and the system as a whole. It can also lead to failures of operations that require physical memory to be present; for example, creating processes, threads, and kernel pool. Thus, you must use the SetProcessWorkingSetSize function carefully. You must always consider the performance of the whole system when you are designing an application.

Requirements

Client	Requires Windows XP, Windows 2000 Professional, or Windows NT Workstation 3.5 and later.
Server	Requires Windows Server 2003, Windows 2000 Server, or Windows NT Server 3.5 and later.
Header	Declared in Winbase.h; include Windows.h.
Library	Link to Kernel32.lib.
DLL	Requires Kernel32.dll.