最快的定时分辨率系统 [英] Fastest timing resolution system

问题描述

什么是最快的计时系统中的C / C ++程序员可以使用？

例如：结果
时间（）将给秒自1970年1月1日00:00。结果
的GetTickCount（）在Windows会给时间，以毫秒为单位，因为系统的启动时间，但仅限49.7天（这只是包装回零后）。

我想获得当前时间，或因为系统/应用程序的启动时间刻度，以毫秒为单位。

最大的担忧是该方法的开销 - 我需要最轻的一个，因为我即将把它称为很多很多次每秒

。

我的情况是，我有一个工作线程，并且该工作线程我张贴的暂挂作业。每个职业都有一个执行时间。所以，我不在乎，如果时间是当前的真正的时间或因为系统的正常运行时间 - 它只是必须是线性光

。

编辑：

 无符号__int64 GetTickCountEx（）
{
    静态DWORD dwWraps = 0;
    静态DWORD dwLast = 0;    DWORD dwCurrent = 0;    timeMutex.lock（）;    dwCurrent =的GetTickCount（）;
    如果（dwLast＆GT; dwCurrent）
        dwWraps ++;    dwLast = dwCurrent;    无符号__int64 timeResult =（（无符号__int64）0xFFFFFFFF的* dwWraps）+ dwCurrent;    timeMutex.unlock（）;    返回timeResult;
}
 

解决方案

有关计时，目前微软推荐是使用<一个href=\"http://msdn.microsoft.com/en-us/library/ms886788.aspx\"><$c$c>QueryPerformanceCounter ＆安培; <一href=\"http://msdn.microsoft.com/en-us/library/ms886788.aspx\"><$c$c>QueryPerformanceFrequency.

这会给你优于毫秒的时间。如果系统不支持高分辨率定时器，那么它会默认为毫秒（同为的GetTickCount ）。

这里是一个简短微软的文章与你为什么要使用它例子：）

What is the fastest timing system a C/C++ programmer can use?

For example:
time() will give the seconds since Jan 01 1970 00:00.
GetTickCount() on Windows will give the time, in milliseconds, since the system's start-up time, but is limited to 49.7 days (after that it simply wraps back to zero).

I want to get the current time, or ticks since system/app start-up time, in milliseconds.

The biggest concern is the method's overhead - I need the lightest one, because I'm about to call it many many times per second.

My case is that I have a worker thread, and to that worker thread I post pending jobs. Each job has an "execution time". So, I don't care if the time is the current "real" time or the time since the system's uptime - it just must be linear and light.

Edit:

unsigned __int64 GetTickCountEx()
{
    static DWORD dwWraps = 0;
    static DWORD dwLast = 0;

    DWORD dwCurrent = 0;

    timeMutex.lock();

    dwCurrent = GetTickCount();
    if(dwLast > dwCurrent)
        dwWraps++;

    dwLast = dwCurrent;

    unsigned __int64 timeResult = ((unsigned __int64)0xFFFFFFFF * dwWraps) + dwCurrent;

    timeMutex.unlock();

    return timeResult;
}

解决方案

For timing, the current Microsoft recommendation is to use QueryPerformanceCounter & QueryPerformanceFrequency.

This will give you better-than-millisecond timing. If the system doesn't support a high-resolution timer, then it will default to milliseconds (the same as GetTickCount).

Here is a short Microsoft article with examples of why you should use it :)

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