using System;
using System.Runtime.InteropServices;
public class A
{
[DllImport("kernel32.dll")]
static extern bool QueryPerformanceCounter([In, Out] ref long lpPerformanceCount);
[DllImport("kernel32.dll")]
static extern bool QueryPerformanceFrequency([In, Out] ref long lpFrequency);
static long _f = 0;
static public long GetTickCount()
{
long f = _f;
if (f == 0)
{
if (QueryPerformanceFrequency(ref f))
{
_f = f;
}
else
{
_f = -1;
}
}
if (f == -1)
{
return Environment.TickCount * 10000;
}
long c = 0;
QueryPerformanceCounter(ref c);
return (long)(((double)c) * 1000 * 10000 / ((double)f));
}
//GetTickCount()为0时的DateTime.Ticks值
static long _tc = 0;
//这个返回的不是真正的精确时间，但时间与时间的差是精确的。
//GetExactNow与DateTime.Now的偏差比DateTime.Now的精度还要小，所以该偏差
static public DateTime GetExactNow()
{
if (_tc == 0)
{
long tc = GetTickCount();
DateTime dt = DateTime.Now;
_tc = dt.Ticks - tc;
return dt;
}
return new DateTime(_tc + GetTickCount());
}
}
在ASP。NET的应用，可以在Global.asax的Application_BeginRequest事件中加入代码来纪录程序开始时的TickCount：
context.items["beginrequesttickcount"]=a.gettickcount();
然后在页面输出的后面：
<html>....
<div align="center">
<%=new TimeSpan(A.GetTickCount()-(long)Context.Items["BeginRequestTickCount"]).TotalMilliseconds%>
</div>
</body></html>
