WinAPI Sleep() 函数调用休眠的时间比预期的要长 [英] WinAPI Sleep() function call sleeps for longer than expected

问题描述

操作系统:Windows 7

OS: Windows 7

当调用 WinAPI Sleep() 函数作为 Sleep(1) 时，线程实际上会休眠 15 毫秒.我循环了 100 次，总睡眠时间是 1500 毫秒而不是 100 毫秒.

When calling the WinAPI Sleep() function as Sleep(1) the thread actually sleeps for 15ms. I did it 100 times in a loop and the total sleep time was 1500ms instead of 100.

这是常见行为还是我应该担心我的 MOBO、CPU、Windows 安装出现问题?

Is this common behavior or should I be concerced about something being wrong with my MOBO, CPU, Windows installion?

如果可能，您可以运行此代码并发布睡眠时间有多长.我让我的一个朋友运行了这个，他实际上在 1 毫秒内就完成了.

If possible could you run this code and post how long the sleep time was. I let a friend of mine run this, and he actually had it all at 1ms.

#include <iostream>
#include <ctime>
#include <Windows.h>

void test(void)
{
    std::cout << "Testing 1ms sleep." << std::endl;

    for (unsigned int i = 0; i < 10; i++)
    {
        std::clock_t startClocks = std::clock();

        Sleep(1);

        std::clock_t clocksTaken = std::clock() - startClocks;
        std::cout << "Time: " << clocksTaken << "ms." << std::endl;
    }
}

int main(void)
{
    test();

    std::cin.sync();
    std::cin.get();
    return 0;
}

似乎有些人得到 1ms 的原因是其他一些程序正在运行，将系统范围的计时器分辨率设置为 1ms.默认情况下，这在 Windows 7 上应该是 15.6 毫秒.

It seems that the reason why some people are getting 1ms is that some other program is running that sets the system-wide timer resolution to 1ms. By default this should be 15.6ms on Windows 7.

推荐答案

这是常见的行为吗

Is this common behavior

是的.

Window 的线程调度程序在时间片上工作(确切长度取决于各种因素，包括 Windows 版本和版本).实际上，任何非零延迟都会向上舍入为一个完整的量程.

Window's thread scheduler works on a time quantum (exact length depends of various factors including Windows version and edition). Effectively any non-zero delay is rounded up to a complete quantum.

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