最近我的系统内存不足有问题。我花了一段时间才发现发生了什么，但我最终确定当我从文件共享中将大量数据复制到我的机器时，相当大量的内存被放入“待机”状态。任务管理器似乎没有显示备用内存使用情况，但资源监视器显示。起初我只能通过重新启动来恢复内存，但最终我发现SysInternals的人已经编写了一个很棒的实用工具来释放内存（链接如下）。
以下是备用内存的简要介绍：
备用列表包含已从进程工作集中删除的未修改页面，这有效地使备用列表成为缓存。如果进程需要待机列表中的页面，则内存管理器会立即将页面返回到其工作集。 待机列表中的所有页面都可用于内存分配请求。如果进程请求内存，则内存管理器可以从待机列表中获取页面，对其进行初始化，并将其分配给调用进程。这称为重新调整页面。 待机列表中的页面通常来自最近使用的文件。通过将这些页面保留在待机列表中，内存管理器减少了从磁盘读取信息的需要。磁盘读取会降低系统响应能力。
（这是来自此处的文件：Memory Sizing Guidance
以下是该工具的链接： RAMMap
我的问题是：
有没有人知道这是如何以编程方式进行的？理想情况下我想使用C＃，但我会感谢任何可能帮助我得到答案的指针。
谢谢！
答案 0 :(得分：3)
这是我的代码，它是一个必须以管理员权限运行的控制台应用程序。代码是C＃。 使用EmptyWorkingSet和MemoryPurgeStandbyList。
using System;
using System.ComponentModel;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Security.Principal;
using System.Threading;
using System.Collections.Generic;
namespace FreeMemory
{
//Declaration of structures
//SYSTEM_CACHE_INFORMATION
[StructLayout(LayoutKind.Sequential, Pack = 1)]
struct SYSTEM_CACHE_INFORMATION
{
public uint CurrentSize;
public uint PeakSize;
public uint PageFaultCount;
public uint MinimumWorkingSet;
public uint MaximumWorkingSet;
public uint Unused1;
public uint Unused2;
public uint Unused3;
public uint Unused4;
}
//SYSTEM_CACHE_INFORMATION_64_BIT
[StructLayout(LayoutKind.Sequential, Pack = 1)]
struct SYSTEM_CACHE_INFORMATION_64_BIT
{
public long CurrentSize;
public long PeakSize;
public long PageFaultCount;
public long MinimumWorkingSet;
public long MaximumWorkingSet;
public long Unused1;
public long Unused2;
public long Unused3;
public long Unused4;
}
//TokPriv1Luid
[StructLayout(LayoutKind.Sequential, Pack = 1)]
internal struct TokPriv1Luid
{
public int Count;
public long Luid;
public int Attr;
}
public class Program
{
//Declaration of constants
const int SE_PRIVILEGE_ENABLED = 2;
const string SE_INCREASE_QUOTA_NAME = "SeIncreaseQuotaPrivilege";
const string SE_PROFILE_SINGLE_PROCESS_NAME = "SeProfileSingleProcessPrivilege";
const int SystemFileCacheInformation = 0x0015;
const int SystemMemoryListInformation = 0x0050;
const int MemoryPurgeStandbyList = 4;
const int MemoryEmptyWorkingSets = 2;
//Import of DLL's (API) and the necessary functions
[DllImport("advapi32.dll", SetLastError = true)]
internal static extern bool LookupPrivilegeValue(string host, string name, ref long pluid);
[DllImport("advapi32.dll", SetLastError = true)]
internal static extern bool AdjustTokenPrivileges(IntPtr htok, bool disall, ref TokPriv1Luid newst, int len, IntPtr prev, IntPtr relen);
[DllImport("ntdll.dll")]
public static extern UInt32 NtSetSystemInformation(int InfoClass, IntPtr Info, int Length);
[DllImport("psapi.dll")]
static extern int EmptyWorkingSet(IntPtr hwProc);
//Function to clear working set of all processes
public static void EmptyWorkingSetFunction()
{
//Declaration of variables
string ProcessName = string.Empty;
Process[] allProcesses = Process.GetProcesses();
List<string> successProcesses = new List<string>();
List<string> failProcesses = new List<string>();
//Cycle through all processes
for (int i = 0; i < allProcesses.Length; i++)
{
Process p = new Process();
p = allProcesses[i];
//Try to empty the working set of the process, if succesfull add to successProcesses, if failed add to failProcesses with error message
try
{
ProcessName = p.ProcessName;
EmptyWorkingSet(p.Handle);
successProcesses.Add(ProcessName);
}
catch (Exception ex)
{
failProcesses.Add(ProcessName + ": " + ex.Message);
}
}
//Print the lists with successful and failed processes
Console.WriteLine("SUCCESSFULLY CLEARED PROCESSES: " + successProcesses.Count);
Console.WriteLine("-------------------------------");
for (int i = 0; i < successProcesses.Count; i++)
{
Console.WriteLine(successProcesses[i]);
}
Console.WriteLine();
Console.WriteLine("FAILED CLEARED PROCESSES: " + failProcesses.Count);
Console.WriteLine("-------------------------------");
for (int i = 0; i < failProcesses.Count; i++)
{
Console.WriteLine(failProcesses[i]);
}
Console.WriteLine();
}
//Function to check if OS is 64-bit or not, returns boolean
public static bool Is64BitMode()
{
return Marshal.SizeOf(typeof(IntPtr)) == 8;
}
//Function used to clear file system cache, returns boolean
public static void ClearFileSystemCache(bool ClearStandbyCache)
{
try
{
//Check if privilege can be increased
if (SetIncreasePrivilege(SE_INCREASE_QUOTA_NAME))
{
uint num1;
int SystemInfoLength;
GCHandle gcHandle;
//First check which version is running, then fill structure with cache information. Throw error is cache information cannot be read.
if (!Is64BitMode())
{
SYSTEM_CACHE_INFORMATION cacheInformation = new SYSTEM_CACHE_INFORMATION();
cacheInformation.MinimumWorkingSet = uint.MaxValue;
cacheInformation.MaximumWorkingSet = uint.MaxValue;
SystemInfoLength = Marshal.SizeOf(cacheInformation);
gcHandle = GCHandle.Alloc(cacheInformation, GCHandleType.Pinned);
num1 = NtSetSystemInformation(SystemFileCacheInformation, gcHandle.AddrOfPinnedObject(), SystemInfoLength);
gcHandle.Free();
}
else
{
SYSTEM_CACHE_INFORMATION_64_BIT information64Bit = new SYSTEM_CACHE_INFORMATION_64_BIT();
information64Bit.MinimumWorkingSet = -1L;
information64Bit.MaximumWorkingSet = -1L;
SystemInfoLength = Marshal.SizeOf(information64Bit);
gcHandle = GCHandle.Alloc(information64Bit, GCHandleType.Pinned);
num1 = NtSetSystemInformation(SystemFileCacheInformation, gcHandle.AddrOfPinnedObject(), SystemInfoLength);
gcHandle.Free();
}
if (num1 != 0)
throw new Exception("NtSetSystemInformation(SYSTEMCACHEINFORMATION) error: ", new Win32Exception(Marshal.GetLastWin32Error()));
}
//If passes paramater is 'true' and the privilege can be increased, then clear standby lists through MemoryPurgeStandbyList
if (ClearStandbyCache && SetIncreasePrivilege(SE_PROFILE_SINGLE_PROCESS_NAME))
{
int SystemInfoLength = Marshal.SizeOf(MemoryPurgeStandbyList);
GCHandle gcHandle = GCHandle.Alloc(MemoryPurgeStandbyList, GCHandleType.Pinned);
uint num2 = NtSetSystemInformation(SystemMemoryListInformation, gcHandle.AddrOfPinnedObject(), SystemInfoLength);
gcHandle.Free();
if (num2 != 0)
throw new Exception("NtSetSystemInformation(SYSTEMMEMORYLISTINFORMATION) error: ", new Win32Exception(Marshal.GetLastWin32Error()));
}
}
catch (Exception ex)
{
Console.Write(ex.ToString());
}
}
//Function to increase Privilege, returns boolean
private static bool SetIncreasePrivilege(string privilegeName)
{
using (WindowsIdentity current = WindowsIdentity.GetCurrent(TokenAccessLevels.Query | TokenAccessLevels.AdjustPrivileges))
{
TokPriv1Luid newst;
newst.Count = 1;
newst.Luid = 0L;
newst.Attr = SE_PRIVILEGE_ENABLED;
//Retrieves the LUID used on a specified system to locally represent the specified privilege name
if (!LookupPrivilegeValue(null, privilegeName, ref newst.Luid))
throw new Exception("Error in LookupPrivilegeValue: ", new Win32Exception(Marshal.GetLastWin32Error()));
//Enables or disables privileges in a specified access token
int num = AdjustTokenPrivileges(current.Token, false, ref newst, 0, IntPtr.Zero, IntPtr.Zero) ? 1 : 0;
if (num == 0)
throw new Exception("Error in AdjustTokenPrivileges: ", new Win32Exception(Marshal.GetLastWin32Error()));
return num != 0;
}
}
//MAIN Program
static void Main(string[] args)
{
//Clear working set of all processes
EmptyWorkingSetFunction();
//Clear file system cache
ClearFileSystemCache(true);
//Waiting for input of user to close program
Console.WriteLine("Press any key to exit.");
Console.ReadKey();
}
}
}
答案 1 :(得分：2)
秘密似乎是在Process Hacker源代码中（使用c语言）。查看代码，您将看到一个有希望的命令MemoryPurgeStandbyList，当我们在GUI中选择“空备用列表”选项时，它似乎被调用。
memlists.c(227, 35): command = MemoryPurgeStandbyList;
ntexapi.h(1475, 5): MemoryPurgeStandbyList,
答案 2 :(得分：2)
这概述了在C＃
中实现这一目标所需的基本步骤using System;
using System.Runtime.InteropServices;
using System.Security.Principal;
public static class MemoryUtility
{
private static void ClearStandbyCache()
{
SetIncreasePrivilege(SE_PROFILE_SINGLE_PROCESS_NAME);
int iReturn;
int iSize = Marshal.SizeOf(ClearStandbyPageList);
GCHandle gch = GCHandle.Alloc(ClearStandbyPageList, GCHandleType.Pinned);
iReturn = NtSetSystemInformation(SYSTEMMEMORYLISTINFORMATION, gch.AddrOfPinnedObject(), iSize);
gch.Free();
if (iReturn != 0)
Console.WriteLine("Empty Standby List failed");
else
Console.WriteLine("Empty Standby List success");
}
[DllImport("NTDLL.dll", SetLastError = true)]
internal static extern int NtSetSystemInformation(int SystemInformationClass, IntPtr SystemInfo, int SystemInfoLength);
//SystemInformationClass values
private static int SYSTEMCACHEINFORMATION = 0x15;
private static int SYSTEMMEMORYLISTINFORMATION = 80;
//SystemInfo values
private static int ClearStandbyPageList = 4;
}
此处还有一个链接到一个站点的文档，其中记录了SetIncreasePrivilege方法，并且还包含许多有关该主题的有用资源：http://www.pinvoke.net/default.aspx/ntdll/NtSetSystemInformation.html