最近在项目中需要监测某个进程的CPU使用率,原本以为是一个很简单的需求,想用Windows上的性能计数器来进行计算的,但是经过尝试之后,发现Windows性能计数器算出来的值根本不正确,不耐经过互联网的搜索,终于发现了以下计算方法,总的测试,发现结果还是比较精准的。
其实Windows的进程使用率是计算出来的,在一段很短的时间内,计算某进程使用CPU的时间,除以所有进程使用CPU的时间,即为该进程的CPU使用率。具体代码如下:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 | #include <stdio.h> #include <Windows.h> typedef long long int64_t; typedef unsigned long long uint64_t; /// 时间转换 static uint64_t file_time_2_utc(const FILETIME* ftime) { LARGE_INTEGER li; li.LowPart = ftime->dwLowDateTime; li.HighPart = ftime->dwHighDateTime; return li.QuadPart; } /// 获得CPU的核数 static int get_processor_number() { SYSTEM_INFO info; GetSystemInfo(&info); return (int)info.dwNumberOfProcessors; } int get_cpu_usage(int pid) { //cpu数量 static int processor_count_ = -1; //上一次的时间 static int64_t last_time_ = 0; static int64_t last_system_time_ = 0; FILETIME now; FILETIME creation_time; FILETIME exit_time; FILETIME kernel_time; FILETIME user_time; int64_t system_time; int64_t time; int64_t system_time_delta; int64_t time_delta; int cpu = -1; if(processor_count_ == -1) { processor_count_ = get_processor_number(); } GetSystemTimeAsFileTime(&now); HANDLE hProcess = OpenProcess(PROCESS_ALL_ACCESS, false, pid); if (!GetProcessTimes(hProcess, &creation_time, &exit_time, &kernel_time, &user_time)) { return -1; } system_time = (file_time_2_utc(&kernel_time) + file_time_2_utc(&user_time)) / processor_count_; time = file_time_2_utc(&now); if ((last_system_time_ == 0) || (last_time_ == 0)) { last_system_time_ = system_time; last_time_ = time; return -1; } system_time_delta = system_time - last_system_time_; time_delta = time - last_time_; if (time_delta == 0) return -1; cpu = (int)((system_time_delta * 100 + time_delta / 2) / time_delta); last_system_time_ = system_time; last_time_ = time; return cpu; } int main() { while(1) { int cpu; // 参数为进程id cpu = get_cpu_usage(5160); printf("CPU使用率: %d%%\n",cpu); Sleep(1000); } return 0; } |