以下內(nèi)容主要來自http://www.sizeof.cn/html/2010/365.html ，對其中的一些細節(jié)進行了調(diào)整。
最近在項目中需要監(jiān)測某個進程的CPU使用率，原本以為是一個很簡單的需求，想用Windows上的性能計數(shù)器來進行計算的，但是經(jīng)過嘗試之后，發(fā)現(xiàn)Windows性能計數(shù)器算出來的值根本不正確，不耐經(jīng)過互聯(lián)網(wǎng)的搜索，終于發(fā)現(xiàn)了以下計算方法，總的測試，發(fā)現(xiàn)結(jié)果還是比較精準的。
其實Windows的進程使用率是計算出來的，在一段很短的時間內(nèi)，計算某進程使用CPU的時間，除以所有進程使用CPU的時間，即為該進程的CPU使用率。具體代碼如下：#include <stdafx.h>
#include <stdio.h>
#include <Windows.h>
#include <iostream>
using namespace std;
typedef long long int64_t;
typedef unsigned long long uint64_t;
/// 時間轉(zhuǎn)換
static uint64_t file_time_2_utc(const FILETIME* ftime)
{
LARGE_INTEGER li;
li.LowPart = ftime->dwLowDateTime;
li.HighPart = ftime->dwHighDateTime;
return li.QuadPart;
}
/// 獲得CPU的核數(shù)
static int get_processor_number()
{
SYSTEM_INFO info;
GetSystemInfo(&info);
return (int)info.dwNumberOfProcessors;
}
int get_cpu_usage(int pid)
{
//cpu數(shù)量
static int processor_count_ = -1;
//上一次的時間
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 get_cpu_usage(pid);
}
system_time_delta = system_time - last_system_time_;
time_delta = time - last_time_;
if (time_delta == 0)
return get_cpu_usage(pid);
cpu = (int)((system_time_delta * 100 + time_delta / 2) / time_delta);
last_system_time_ = system_time;
last_time_ = time;
return cpu;
}
int main()
{
int cpu;
int process_id;
// 參數(shù)為進程id
cin>>process_id;
while(1)
{
cpu = get_cpu_usage(process_id);
printf("CPU使用率: %d%%\n",cpu);
Sleep(1000);
}
return 0;
}