C#高精度定时器,可用于profiling

如果想准确profiling函数或者代码性能,一个高精度定时器是必备的。
参考这几个资料吧,
http://en.wikipedia.org/wiki/Time_Stamp_Counter

注意rdtsc在多核下的问题
http://msdn.microsoft.com/en-us/library/ee417693%28v=vs.85%29.aspx

最好最方便的还是这个函数QueryPerformanceCounter

jeffz_cn在他的blog中提到另外一种方法,但是不支持windowsXP,而且好像精度上也没有我下面写的这个高。

要注意的是软件定时器都不是非常准的,只是比较准罢了。另外定时器不要加的太多,需要的几个位置加一下就可。

实际上,我以前在C++用到的,也是一样的win32函数:


class HighResolutionTimer
{
private bool isPerfCounterSupported = false;
private Int64 frequency = 0;
// Windows CE native library with QueryPerformanceCounter().
[DllImport("kernel32.dll", SetLastError = true)]
private static extern int QueryPerformanceCounter(ref Int64 count);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern int QueryPerformanceFrequency(ref Int64 frequency);
public HighResolutionTimer()
{
int returnVal = QueryPerformanceFrequency(ref frequency);
if (returnVal != 0 && frequency != 1000)
{
// The performance counter is supported.
isPerfCounterSupported = true;
}
else
{
// The performance counter is not supported. Use
// Environment.TickCount instead.
frequency = 1000;
}
Start();
}

public Int64 Frequency
{
get
{
return frequency;
}
}

public Int64 Value
{
get
{
Int64 tickCount = 0;

if (isPerfCounterSupported)
{
// Get the value here if the counter is supported.
QueryPerformanceCounter(ref tickCount);
return tickCount;
}
else
{
// Otherwise, use Environment.TickCount.
return (Int64)Environment.TickCount;
}
}
}

private Int64 _startValue;
public void Start()
{
_startValue = Value;
}

public Int64 Stop()
{
Int64 stopValue = Value;
return stopValue - _startValue;
}
}

《C#高精度定时器,可用于profiling》有1个想法

发表评论