首先, 感觉是个蛋疼的话题, 不过是做某个软件遇到的.

Windows系统的TaskManager里面其实就有这个功能, 显示一个进程的相关信息, 诸如pid,CPU占用率, 内存, 线程数等.

那么TaskManager是怎么求出某个进程的CPU占用率的呢? 用的NtQuerySystemInformation, NtQueryInformationProcess等吧, 貌似有人Debug过, 看到了这些函数的调用.

不过使用NtQuerySystemInformation这样的函数是有问题的, 1它们不是public的, 2是官方说它们在Vista以后的版本里面可能被修改.

一个可观的替代方案是使用GetSystemTimes和GetProcessTimes:

1 BOOL WINAPI GetSystemTimes( 2   _Out_opt_  LPFILETIME lpIdleTime, 3   _Out_opt_  LPFILETIME lpKernelTime, 4   _Out_opt_  LPFILETIME lpUserTime 5 ); 6  7 BOOL WINAPI GetProcessTimes( 8   _In_   HANDLE hProcess, 9   _Out_  LPFILETIME lpCreationTime,10   _Out_  LPFILETIME lpExitTime,11   _Out_  LPFILETIME lpKernelTime,12   _Out_  LPFILETIME lpUserTime13 );

GetSystemTimes获得系统(自开机以来)处于Kernel状态下面的CPU时间,以及系统处于User状态下的时间,以及Idle的时间.我们只用Kernel时间和User时间, 不用Idle时间.

相应的, GetProcess也能求出一个进程在上面3中状态下的时间.

下面公式可以求出进程的CPU占用率.

　　　　　　　　　　　　　　　　　　

但是事情并没有就此结束, 因为我发现仅仅做上面的工作的话, 在某些系统(当然还是Windows系列...)下面会不奏效, 这就是很多软件开发者考虑的兼容性的问题.

是权限的问题, OpenProcess调用失败是因为你启动的进程没有能够Debug某个进程的权限.

虽然Admin下面有些权限是有的, 但默认的情况下进程的一些访问权限是没有被置为可用状态（即Enabled）的，所以我们要做的首先是使这些权限可用。

下面3个函数基本可以搞定:OpenProcessToken, LookupPrivilegeValue ,AdjustTokenPrivileges(详情见msdn..)

1 HANDLE WINAPI OpenProcess( 2   _In_  DWORD dwDesiredAccess, 3   _In_  BOOL bInheritHandle, 4   _In_  DWORD dwProcessId 5 ); 6  7 BOOL WINAPI OpenProcessToken( 8   _In_   HANDLE ProcessHandle, 9   _In_   DWORD DesiredAccess,10   _Out_  PHANDLE TokenHandle11 );12 13 BOOL WINAPI LookupPrivilegeValue(14   _In_opt_  LPCTSTR lpSystemName,15   _In_      LPCTSTR lpName,16   _Out_     PLUID lpLuid17 );18 19 BOOL WINAPI AdjustTokenPrivileges(20   _In_       HANDLE TokenHandle,21   _In_       BOOL DisableAllPrivileges,22   _In_opt_   PTOKEN_PRIVILEGES NewState,23   _In_       DWORD BufferLength,24   _Out_opt_  PTOKEN_PRIVILEGES PreviousState,25   _Out_opt_  PDWORD ReturnLength26 );

下面是获取进程CPU percent的完整代码:

1 //CpuUsage.h  2 #ifndef _CPU_USAGE_H_  3 #define _CPU_USAGE_H_  4   5 #include 
         
            6   7 class CpuUsage  8 {  9 public: 10     CpuUsage(DWORD dwProcessID); 11     ULONGLONG GetUsageEx(); 12     ULONGLONG GetSystemNonIdleTimes(); 13     ULONGLONG GetProcessNonIdleTimes(); 14 private: 15     ULONGLONG SubtractTimes(const FILETIME& ftA, const FILETIME& ftB); 16     ULONGLONG AddTimes(const FILETIME& ftA, const FILETIME& ftB); 17     bool EnoughTimePassed(); 18     inline bool IsFirstRun() const { return (m_dwLastRun == 0); } 19  20     //system total times 21     FILETIME m_ftPrevSysKernel; 22     FILETIME m_ftPrevSysUser; 23  24     //process times 25     FILETIME m_ftPrevProcKernel; 26     FILETIME m_ftPrevProcUser; 27  28     ULONGLONG m_ullPrevSysNonIdleTime;//这个变量和后面的便利记录上次获取的非idle的系统cpu时间和进程cpu时间. 29     ULONGLONG m_ullPrevProcNonIdleTime;//这个类只绑定一个进程, 在构造函数里面初始化进来.. 30  31     ULONGLONG m_nCpuUsage; 32     ULONGLONG m_dwLastRun; 33     DWORD m_dwProcessID; 34     HANDLE m_hProcess; 35     volatile LONG m_lRunCount; 36 }; 37  38 #endif 39  40  41 //CpuUsage.cpp 42  43 #include 
          
            44 #include "CPUusage.h" 45 #include 
           
             46 //#define USE_DEPRECATED_FUNCS 47 void ErrorMsg(LPTSTR lpszFunction); 48 BOOL SetPrivilege(HANDLE hProcess, LPCTSTR lpszPrivilege, BOOL bEnablePrivilege); 49  50 #ifdef USE_DEPRECATED_FUNCS 51 #define SystemBasicInformation                    0 52 #define SystemPerformanceInformation            2 53 #define SystemTimeInformation                    3 54 #define SystemProcessorPerformanceInformation    8 55 #define ProcessTimes                            4 56  57 #define Li2Double(x) ((double)((x).HighPart) * 4.294967296E9 + (double)((x).LowPart)) 58  59 typedef struct 60 { 61     DWORD dwUnknown1; 62     ULONG uKeMaximumIncrement; 63     ULONG uPageSize; 64     ULONG uMmNumberOfPhysicalPages; 65     ULONG uMmLowestPhysicalPage; 66     ULONG uMmHighestPhysicalPage; 67     ULONG uAllocationGranularity; 68     PVOID pLowestUserAddress; 69     PVOID pMmHighestUserAddress; 70     ULONG uKeActiveProcessors; 71     BYTE bKeNumberProcessors; 72     BYTE bUnknown2; 73     WORD wUnknown3; 74 } SYSTEM_BASIC_INFORMATION; 75  76 typedef struct 77 { 78     LARGE_INTEGER liIdleTime; 79     DWORD dwSpare[312]; 80 } SYSTEM_PERFORMANCE_INFORMATION; 81  82 typedef struct 83 { 84     LARGE_INTEGER liKeBootTime; 85     LARGE_INTEGER liKeSystemTime; 86     LARGE_INTEGER liExpTimeZoneBias; 87     ULONG uCurrentTimeZoneId; 88     DWORD dwReserved; 89 } SYSTEMTEXTIME_INFORMATION; 90  91 typedef struct 92         _SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION 93 { 94     LARGE_INTEGER IdleTime; 95     LARGE_INTEGER KernelTime; 96     LARGE_INTEGER UserTime; 97     LARGE_INTEGER Reserved1[2]; 98     ULONG Reserved2; 99 } SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION;100 101 typedef struct _KERNEL_USERTEXTIMES102 {103     LARGE_INTEGER CreateTime;104     LARGE_INTEGER ExitTime;105     LARGE_INTEGER KernelTime;106     LARGE_INTEGER UserTime;107 } KERNEL_USERTEXTIMES, *PKERNEL_USERTEXTIMES;108 109 typedef LONG (WINAPI *PROCNTQSI)(UINT, PVOID, ULONG, PULONG);110 PROCNTQSI NtQuerySystemInformation;111 112 typedef LONG (WINAPI *PROCNTQIP)(HANDLE, UINT, PVOID, ULONG, PULONG);113 PROCNTQIP NtQueryInformationProcess;114 115 ULONGLONG CpuUsage::GetSystemNonIdleTimes()116 {117     SYSTEM_PERFORMANCE_INFORMATION SysPerfInfo;118     SYSTEMTEXTIME_INFORMATION SysTimeInfo;119     SYSTEM_BASIC_INFORMATION SysBaseInfo;120     SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION SysProcPerfInfo[32];121     LONG status;122     NtQuerySystemInformation = (PROCNTQSI)GetProcAddress(GetModuleHandle(TEXT("ntdll")), "NtQuerySystemInformation");123     if (!NtQuerySystemInformation)124         return 0;125     status = NtQuerySystemInformation(SystemBasicInformation, &SysBaseInfo, sizeof(SysBaseInfo), NULL);126     if (status != NO_ERROR)127     {128         MessageBox(TEXT("FailSystemInfo"));129         return 0;130     }131     status = NtQuerySystemInformation(SystemProcessorPerformanceInformation, SysProcPerfInfo, sizeof(SysProcPerfInfo), NULL);132     if(status != NO_ERROR) return 0;133     int nProcessors = SysBaseInfo.bKeNumberProcessors; //机器内部CPU的个数134     ULONGLONG ullSysTotal = 0;135     for(int i = 0; i < nProcessors; i++)136     {137         ullSysTotal += SysProcPerfInfo[i].KernelTime.QuadPart + SysProcPerfInfo[i].UserTime.QuadPart;138     }139     return ullSysTotal;140 }141 142 ULONGLONG CpuUsage::GetProcessNonIdleTimes()143 {144     KERNEL_USERTEXTIMES KernelUserTimes;145     ::ZeroMemory(&KernelUserTimes, sizeof(KernelUserTimes));146     NtQueryInformationProcess = (PROCNTQIP)GetProcAddress(GetModuleHandle(TEXT("ntdll")), "NtQueryInformationProcess");147     LONG status = NtQueryInformationProcess(m_hProcess, ProcessTimes, &KernelUserTimes, sizeof(KernelUserTimes), NULL);148     if(status == 0)149     {150         ErrorExit(TEXT("GetProcessNonIdleTimes"));151         return 0;152     }153     return KernelUserTimes.KernelTime.QuadPart + KernelUserTimes.UserTime.QuadPart;154 155 }156 157 #endif158 159 CpuUsage::CpuUsage(DWORD dwProcessID)160     : m_nCpuUsage(0),161       m_dwLastRun(0),162       m_lRunCount(0),163       m_dwProcessID(dwProcessID),164       m_ullPrevProcNonIdleTime(0),165       m_ullPrevSysNonIdleTime(0)166 {167     HANDLE hProcess = GetCurrentProcess();168     SetPrivilege(hProcess, SE_DEBUG_NAME, TRUE);169 170     m_hProcess = ::OpenProcess(PROCESS_QUERY_INFORMATION , TRUE, m_dwProcessID);171     if(m_hProcess == 0)172     {173         ErrorMsg(TEXT("OpenProcess"));174     }175     ZeroMemory(&m_ftPrevSysKernel, sizeof(FILETIME));176     ZeroMemory(&m_ftPrevSysUser, sizeof(FILETIME));177 178     ZeroMemory(&m_ftPrevProcKernel, sizeof(FILETIME));179     ZeroMemory(&m_ftPrevProcUser, sizeof(FILETIME));180 }181 182 183 ULONGLONG CpuUsage::SubtractTimes(const FILETIME &ftA, const FILETIME &ftB)184 {185     LARGE_INTEGER a, b;186     a.LowPart = ftA.dwLowDateTime;187     a.HighPart = ftA.dwHighDateTime;188 189     b.LowPart = ftB.dwLowDateTime;190     b.HighPart = ftB.dwHighDateTime;191 192     return a.QuadPart - b.QuadPart;193 }194 195 ULONGLONG CpuUsage::AddTimes(const FILETIME &ftA, const FILETIME &ftB)196 {197     LARGE_INTEGER a, b;198     a.LowPart = ftA.dwLowDateTime;199     a.HighPart = ftA.dwHighDateTime;200 201     b.LowPart = ftB.dwLowDateTime;202     b.HighPart = ftB.dwHighDateTime;203 204     return a.QuadPart + b.QuadPart;205 }206 207 bool CpuUsage::EnoughTimePassed()208 {209     const int minElapsedMS = 250;//milliseconds210 211     ULONGLONG dwCurrentTickCount = GetTickCount();212     return (dwCurrentTickCount - m_dwLastRun) > minElapsedMS;213 }214 #ifndef USE_DEPRECATED_FUNCS215 216 ULONGLONG CpuUsage::GetSystemNonIdleTimes()217 {218     FILETIME ftSysIdle, ftSysKernel, ftSysUser;219     if(!GetSystemTimes(&ftSysIdle, &ftSysKernel, &ftSysUser))220     {221         ErrorMsg(TEXT("GetSystemTimes"));222         return 0;223     }224     return AddTimes(ftSysKernel, ftSysUser);225 }226 227 228 ULONGLONG CpuUsage::GetProcessNonIdleTimes()229 {230     FILETIME ftProcCreation, ftProcExit, ftProcKernel, ftProcUser;231     if(!GetProcessTimes(m_hProcess, &ftProcCreation, &ftProcExit, &ftProcKernel, &ftProcUser) && false)232     {233         ErrorMsg(TEXT("GetProcessNonIdleTimes"));234         return 0;235     }236     return AddTimes(ftProcKernel, ftProcUser);237 }238 #endif239 240 ULONGLONG CpuUsage::GetUsageEx()241 {242     ULONGLONG nCpuCopy = m_nCpuUsage;243     if (::InterlockedIncrement(&m_lRunCount) == 1)244     {245         if (!EnoughTimePassed())246         {247             ::InterlockedDecrement(&m_lRunCount);248             return nCpuCopy;249         }250         ULONGLONG ullSysNonIdleTime = GetSystemNonIdleTimes();251         ULONGLONG ullProcNonIdleTime = GetProcessNonIdleTimes();252         if (!IsFirstRun())253         {254             ULONGLONG ullTotalSys = ullSysNonIdleTime - m_ullPrevSysNonIdleTime;255             if(ullTotalSys == 0)256             {257                 ::InterlockedDecrement(&m_lRunCount);258                 return nCpuCopy;259             }260             m_nCpuUsage = ULONGLONG((ullProcNonIdleTime - m_ullPrevProcNonIdleTime) * 100.0 / (ullTotalSys));261             m_ullPrevSysNonIdleTime = ullSysNonIdleTime;262             m_ullPrevProcNonIdleTime = ullProcNonIdleTime;263         }264         m_dwLastRun = (ULONGLONG)GetTickCount();265         nCpuCopy = m_nCpuUsage;266     }267     ::InterlockedDecrement(&m_lRunCount);268     return nCpuCopy;269 }270 271 BOOL SetPrivilege(HANDLE hProcess, LPCTSTR lpszPrivilege, BOOL bEnablePrivilege)272 {273     HANDLE hToken;274     if(!OpenProcessToken(hProcess, TOKEN_ADJUST_PRIVILEGES, &hToken))275     {276         ErrorMsg(TEXT("OpenProcessToken"));277         return FALSE;278     }279     LUID luid;280     if(!LookupPrivilegeValue(NULL, lpszPrivilege, &luid))281     {282         ErrorMsg(TEXT("LookupPrivilegeValue"));283         return FALSE;284     }285     TOKEN_PRIVILEGES tkp;286     tkp.PrivilegeCount = 1;287     tkp.Privileges[0].Luid = luid;288     tkp.Privileges[0].Attributes = (bEnablePrivilege) ? SE_PRIVILEGE_ENABLED : FALSE;289     if(!AdjustTokenPrivileges(hToken, FALSE, &tkp, sizeof(TOKEN_PRIVILEGES), (PTOKEN_PRIVILEGES)NULL, (PDWORD)NULL))290     {291         ErrorMsg(TEXT("AdjustTokenPrivileges"));292         return FALSE;293     }294     return TRUE;295 }296 297 void ErrorMsg(LPTSTR lpszFunction)298 {299     // Retrieve the system error message for the last-error code300 301     LPVOID lpMsgBuf;302     LPVOID lpDisplayBuf;303     DWORD dw = GetLastError();304 305     FormatMessage(306         FORMAT_MESSAGE_ALLOCATE_BUFFER |307         FORMAT_MESSAGE_FROM_SYSTEM |308         FORMAT_MESSAGE_IGNORE_INSERTS,309         NULL,310         dw,311         LANG_USER_DEFAULT,312         (LPTSTR) &lpMsgBuf,313         0, NULL );314 315     // Display the error message316 317     lpDisplayBuf = (LPVOID)LocalAlloc(LMEM_ZEROINIT,318                                       (lstrlen((LPCTSTR)lpMsgBuf) + lstrlen((LPCTSTR)lpszFunction) + 40) * sizeof(TCHAR));319     StringCchPrintf((LPTSTR)lpDisplayBuf,320                     LocalSize(lpDisplayBuf) / sizeof(TCHAR),321                     TEXT("%s failed with error %d: %s"),322                     lpszFunction, dw, lpMsgBuf);323     MessageBox(NULL, (LPCTSTR)lpDisplayBuf, TEXT("Error"), MB_OK);324 325     LocalFree(lpMsgBuf);326     LocalFree(lpDisplayBuf);327     ExitProcess(dw);328 }329 330 //main.cpp331 332 #include "cpuusage.h"333 #include 
            
             334 #include 
             
              335 #include 
              
               336 using namespace std;337 338 const int second = 1000;339 340 int main(int argc, char* argv[])341 {342 if(argc != 2)343 {344 printf("Use the toolkit like: 
                
                
                 \n");345 return 0;346 }347 DWORD dwProcId = atoi(argv[1]);348 CpuUsage cu(dwProcId);349 SYSTEMTIME st;350 while(true)351 {352 GetLocalTime(&st);353 printf("Process(pid:%d) uses %I64d%% cpu at %02d:%02d.%02d\n", dwProcId, cu.GetUsageEx(), st.wHour, st.wMinute, st.wSecond);354 ::Sleep(second);355 }356 }
                
               
              
             
            
           
          
         

搞上面那坨代码的时候我发现了ProcessHacker, 它是个开源版本的Process Explorer, 如果你对Windows里面那些乌七八糟的东西感兴趣的话, 可以看看.

ProcessHacker: