c++ - 如何从进程内部确定 CPU 和内存消耗

Question

我曾经的任务是从正在运行的应用程序内部确定以下性能参数:

• 可用虚拟内存总量
• 当前使用的虚拟内存
• 我的进程当前使用的虚拟内存

  ---

• 可用内存总量
• 当前使用的内存
• 我的进程当前使用的 RAM

  ---

• 当前使用的 CPU 百分比
• 我的进程当前使用的 CPU 百分比

代码必须在 Windows 和 Linux 上运行。尽管这似乎是一项标准任务，但在手册(WIN32 API、GNU 文档)以及互联网上找到必要的信息还是花了我好几天的时间，因为关于这个主题的信息太多不完整/不正确/过时了在那里发现。

为了避免其他人遇到同样的麻烦，我认为将所有分散的信息以及我通过反复试验发现的信息收集在一个地方是个好主意。

Answer 1

window

上面的一些值可以很容易地从适当的 Win32 API 中获得，为了完整起见，我只是在这里列出它们。然而，其他的则需要从 Performance Data Helper 库 (PDH) 中获取，这有点“不直观”并且需要大量痛苦的试验和错误才能开始工作。 (至少花了我不少时间，也许我只是笨了点……)

注意:为清楚起见，以下代码省略了所有错误检查。请检查返回代码...!

• 总虚拟内存:

  #include "windows.h"
  
  MEMORYSTATUSEX memInfo;
  memInfo.dwLength = sizeof(MEMORYSTATUSEX);
  GlobalMemoryStatusEx(&memInfo);
  DWORDLONG totalVirtualMem = memInfo.ullTotalPageFile;
  

  注意:名称“TotalPageFile”在这里有点误导。实际上，此参数给出了“虚拟内存大小”，即交换文件的大小加上已安装的 RAM。

• 当前使用的虚拟内存:

  与“Total Virtual Memory”中的代码相同

   DWORDLONG virtualMemUsed = memInfo.ullTotalPageFile - memInfo.ullAvailPageFile;
  

• 当前进程使用的虚拟内存:

  #include "windows.h"
  #include "psapi.h"
  
  PROCESS_MEMORY_COUNTERS_EX pmc;
  GetProcessMemoryInfo(GetCurrentProcess(), (PROCESS_MEMORY_COUNTERS*)&pmc, sizeof(pmc));
  SIZE_T virtualMemUsedByMe = pmc.PrivateUsage;
  

• 总物理内存 (RAM):

  与“Total Virtual Memory”中的代码相同

  DWORDLONG totalPhysMem = memInfo.ullTotalPhys;
  

• 当前使用的物理内存:

  与“Total Virtual Memory”中的代码相同

  DWORDLONG physMemUsed = memInfo.ullTotalPhys - memInfo.ullAvailPhys;
  

• 当前进程当前使用的物理内存:

  与“当前进程当前使用的虚拟内存”中的代码相同，然后

  SIZE_T physMemUsedByMe = pmc.WorkingSetSize;
  

• 当前使用的 CPU:

  #include "TCHAR.h"
  #include "pdh.h"
  
  static PDH_HQUERY cpuQuery;
  static PDH_HCOUNTER cpuTotal;
  
  void init(){
      PdhOpenQuery(NULL, NULL, &cpuQuery);
      // You can also use L"\\Processor(*)\\% Processor Time" and get individual CPU values with PdhGetFormattedCounterArray()
      PdhAddEnglishCounter(cpuQuery, L"\\Processor(_Total)\\% Processor Time", NULL, &cpuTotal);
      PdhCollectQueryData(cpuQuery);
  }
  
  double getCurrentValue(){
      PDH_FMT_COUNTERVALUE counterVal;
  
      PdhCollectQueryData(cpuQuery);
      PdhGetFormattedCounterValue(cpuTotal, PDH_FMT_DOUBLE, NULL, &counterVal);
      return counterVal.doubleValue;
  }
  

• 当前进程当前使用的 CPU:

  #include "windows.h"
  
  static ULARGE_INTEGER lastCPU, lastSysCPU, lastUserCPU;
  static int numProcessors;
  static HANDLE self;
  
  void init(){
      SYSTEM_INFO sysInfo;
      FILETIME ftime, fsys, fuser;
  
      GetSystemInfo(&sysInfo);
      numProcessors = sysInfo.dwNumberOfProcessors;
  
      GetSystemTimeAsFileTime(&ftime);
      memcpy(&lastCPU, &ftime, sizeof(FILETIME));
  
      self = GetCurrentProcess();
      GetProcessTimes(self, &ftime, &ftime, &fsys, &fuser);
      memcpy(&lastSysCPU, &fsys, sizeof(FILETIME));
      memcpy(&lastUserCPU, &fuser, sizeof(FILETIME));
  }
  
  double getCurrentValue(){
      FILETIME ftime, fsys, fuser;
      ULARGE_INTEGER now, sys, user;
      double percent;
  
      GetSystemTimeAsFileTime(&ftime);
      memcpy(&now, &ftime, sizeof(FILETIME));
  
      GetProcessTimes(self, &ftime, &ftime, &fsys, &fuser);
      memcpy(&sys, &fsys, sizeof(FILETIME));
      memcpy(&user, &fuser, sizeof(FILETIME));
      percent = (sys.QuadPart - lastSysCPU.QuadPart) +
          (user.QuadPart - lastUserCPU.QuadPart);
      percent /= (now.QuadPart - lastCPU.QuadPart);
      percent /= numProcessors;
      lastCPU = now;
      lastUserCPU = user;
      lastSysCPU = sys;
  
      return percent * 100;
  }
  

---

Linux

在 Linux 上，一开始似乎很明显的选择是使用 POSIX API，如 getrusage() 等。我花了一些时间试图让它工作，但从未得到有意义的值。当我最终自己检查内核源代码时，我发现显然这些 API 在 Linux 内核 2.6 中还没有完全实现!？

最后，我通过读取伪文件系统 /proc 和内核调用的组合获得了所有值。

• 总虚拟内存:

  #include "sys/types.h"
  #include "sys/sysinfo.h"
  
  struct sysinfo memInfo;
  
  sysinfo (&memInfo);
  long long totalVirtualMem = memInfo.totalram;
  //Add other values in next statement to avoid int overflow on right hand side...
  totalVirtualMem += memInfo.totalswap;
  totalVirtualMem *= memInfo.mem_unit;
  

• 当前使用的虚拟内存:

  与“Total Virtual Memory”中的代码相同

  long long virtualMemUsed = memInfo.totalram - memInfo.freeram;
  //Add other values in next statement to avoid int overflow on right hand side...
  virtualMemUsed += memInfo.totalswap - memInfo.freeswap;
  virtualMemUsed *= memInfo.mem_unit;
  

• 当前进程使用的虚拟内存:

  #include "stdlib.h"
  #include "stdio.h"
  #include "string.h"
  
  int parseLine(char* line){
      // This assumes that a digit will be found and the line ends in " Kb".
      int i = strlen(line);
      const char* p = line;
      while (*p <'0' || *p > '9') p++;
      line[i-3] = '\0';
      i = atoi(p);
      return i;
  }
  
  int getValue(){ //Note: this value is in KB!
      FILE* file = fopen("/proc/self/status", "r");
      int result = -1;
      char line[128];
  
      while (fgets(line, 128, file) != NULL){
          if (strncmp(line, "VmSize:", 7) == 0){
              result = parseLine(line);
              break;
          }
      }
      fclose(file);
      return result;
  }
  

• 总物理内存 (RAM):

  与“Total Virtual Memory”中的代码相同

  long long totalPhysMem = memInfo.totalram;
  //Multiply in next statement to avoid int overflow on right hand side...
  totalPhysMem *= memInfo.mem_unit;
  

• 当前使用的物理内存:

  与“Total Virtual Memory”中的代码相同

  long long physMemUsed = memInfo.totalram - memInfo.freeram;
  //Multiply in next statement to avoid int overflow on right hand side...
  physMemUsed *= memInfo.mem_unit;
  

• 当前进程当前使用的物理内存:

  修改“当前进程当前使用的虚拟内存”中的getValue()方法如下:

  int getValue(){ //Note: this value is in KB!
      FILE* file = fopen("/proc/self/status", "r");
      int result = -1;
      char line[128];
  
      while (fgets(line, 128, file) != NULL){
          if (strncmp(line, "VmRSS:", 6) == 0){
              result = parseLine(line);
              break;
          }
      }
      fclose(file);
      return result;
  }
  

• 当前使用的 CPU:

  #include "stdlib.h"
  #include "stdio.h"
  #include "string.h"
  
  static unsigned long long lastTotalUser, lastTotalUserLow, lastTotalSys, lastTotalIdle;
  
  void init(){
      FILE* file = fopen("/proc/stat", "r");
      fscanf(file, "cpu %llu %llu %llu %llu", &lastTotalUser, &lastTotalUserLow,
          &lastTotalSys, &lastTotalIdle);
      fclose(file);
  }
  
  double getCurrentValue(){
      double percent;
      FILE* file;
      unsigned long long totalUser, totalUserLow, totalSys, totalIdle, total;
  
      file = fopen("/proc/stat", "r");
      fscanf(file, "cpu %llu %llu %llu %llu", &totalUser, &totalUserLow,
          &totalSys, &totalIdle);
      fclose(file);
  
      if (totalUser < lastTotalUser || totalUserLow < lastTotalUserLow ||
          totalSys < lastTotalSys || totalIdle < lastTotalIdle){
          //Overflow detection. Just skip this value.
          percent = -1.0;
      }
      else{
          total = (totalUser - lastTotalUser) + (totalUserLow - lastTotalUserLow) +
              (totalSys - lastTotalSys);
          percent = total;
          total += (totalIdle - lastTotalIdle);
          percent /= total;
          percent *= 100;
      }
  
      lastTotalUser = totalUser;
      lastTotalUserLow = totalUserLow;
      lastTotalSys = totalSys;
      lastTotalIdle = totalIdle;
  
      return percent;
  }
  

• 当前进程当前使用的 CPU:

  #include "stdlib.h"
  #include "stdio.h"
  #include "string.h"
  #include "sys/times.h"
  #include "sys/vtimes.h"
  
  static clock_t lastCPU, lastSysCPU, lastUserCPU;
  static int numProcessors;
  
  void init(){
      FILE* file;
      struct tms timeSample;
      char line[128];
  
      lastCPU = times(&timeSample);
      lastSysCPU = timeSample.tms_stime;
      lastUserCPU = timeSample.tms_utime;
  
      file = fopen("/proc/cpuinfo", "r");
      numProcessors = 0;
      while(fgets(line, 128, file) != NULL){
          if (strncmp(line, "processor", 9) == 0) numProcessors++;
      }
      fclose(file);
  }
  
  double getCurrentValue(){
      struct tms timeSample;
      clock_t now;
      double percent;
  
      now = times(&timeSample);
      if (now <= lastCPU || timeSample.tms_stime < lastSysCPU ||
          timeSample.tms_utime < lastUserCPU){
          //Overflow detection. Just skip this value.
          percent = -1.0;
      }
      else{
          percent = (timeSample.tms_stime - lastSysCPU) +
              (timeSample.tms_utime - lastUserCPU);
          percent /= (now - lastCPU);
          percent /= numProcessors;
          percent *= 100;
      }
      lastCPU = now;
      lastSysCPU = timeSample.tms_stime;
      lastUserCPU = timeSample.tms_utime;
  
      return percent;
  }
  

---

TODO:其他平台

我假设，一些 Linux 代码也适用于 Unix，除了读取/proc 伪文件系统的部分。也许在 Unix 上这些部分可以用 getrusage() 和类似的函数代替？