问题描述
我需要找到一个瓶颈，并且需要尽可能准确地测量时间.
I need to find a bottleneck and need to accurately as possible measure time.
以下代码片段是衡量性能的最佳方式吗?
Is the following code snippet the best way to measure the performance?
DateTime startTime = DateTime.Now;
// Some execution process
DateTime endTime = DateTime.Now;
TimeSpan totalTimeTaken = endTime.Subtract(startTime);
推荐答案
不，不是.使用 秒表(在 System.Diagnostics)
No, it's not. Use the Stopwatch (in System.Diagnostics)
Stopwatch sw = Stopwatch.StartNew();
PerformWork();
sw.Stop();
Console.WriteLine("Time taken: {0}ms", sw.Elapsed.TotalMilliseconds);
秒表自动检查是否存在高精度计时器.
Stopwatch automatically checks for the existence of high-precision timers.
值得一提的是，由于必须处理时区，夏令时等.
It is worth mentioning that DateTime.Now often is quite a bit slower than DateTime.UtcNow due to the work that has to be done with timezones, DST and such.
DateTime.UtcNow 通常具有 15 ms 的分辨率.请参阅 John Chapman 的博文，了解 DateTime.现在精确到一个很好的总结.
DateTime.UtcNow typically has a resolution of 15 ms. See John Chapman's blog post about DateTime.Now precision for a great summary.
有趣的琐事:如果您的硬件不支持高频计数器，秒表会退回到 DateTime.UtcNow.您可以通过查看静态字段 Stopwatch.IsHighResolution.
Interesting trivia: The stopwatch falls back on DateTime.UtcNow if your hardware doesn't support a high frequency counter. You can check to see if Stopwatch uses hardware to achieve high precision by looking at the static field Stopwatch.IsHighResolution.
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