c# - 为什么 .NET Core 2.0 的性能比 .NET Framework 4.6.1 差

Question

我编写了一个创建 4 个线程的程序，每个线程将 20.000 个数字从低到高排序 50 次。我已在 .NET Core 2.0 和 .NET Framework 4.6.1 上多次运行此测试。在此测试中，.NET Framework 始终优于 .NET Core。

设置

• .NET Core 处于 Release模式并已发布
• Windows 10，i7 双核，4 线程(超线程)

以下代码已用于对两个框架进行基准测试。

static void Main()
    {
        const int amountParallel = 4;
        var globalStopwatch = new Stopwatch();

        globalStopwatch.Start();

        var tasks = new Task<double[]>[4];

        for (int i = 0; i < amountParallel; i++)
        {
            tasks[i] = Start();
        }

        Task.WaitAll(tasks);

        globalStopwatch.Stop();

        Console.WriteLine("Averages: {0}ms", tasks.SelectMany(r => r.Result).Average(x => x));
        Console.WriteLine("Time completed: {0}", globalStopwatch.Elapsed.TotalMilliseconds);
    }

    private static Task<double[]> Start()
    {
        return Task.Factory.StartNew(() =>
        {
            var numbersToSort = new int[20000];

            var globalStopwatch = new Stopwatch();
            var individualStopwatch = new Stopwatch();
            var stopwatchTimes = new double[50];
            int temp;

            globalStopwatch.Start();

            for (int i = 0; 50 > i; i++)
            {
                Console.WriteLine("Running task: {0}", i);
                numbersToSort = Enumerable.Range(0, 20000).Reverse().ToArray();
                individualStopwatch.Start();

                for (int indexNumberArray = 0; numbersToSort.Length > indexNumberArray; indexNumberArray++)
                {
                    for (int sort = 0; numbersToSort.Length - 1 > sort; sort++)
                    {
                        if (numbersToSort[sort] > numbersToSort[sort + 1])
                        {
                            temp = numbersToSort[sort + 1];
                            numbersToSort[sort + 1] = numbersToSort[sort];
                            numbersToSort[sort] = temp;
                        }
                    }
                }

                individualStopwatch.Stop();

                Console.WriteLine("Task {0} completed, took: {1}ms", i, Math.Round(individualStopwatch.Elapsed.TotalMilliseconds));

                stopwatchTimes[i] = individualStopwatch.Elapsed.TotalMilliseconds;

                individualStopwatch.Reset();
            }

            globalStopwatch.Stop();

            Console.WriteLine("Total time: {0}s", Math.Round(globalStopwatch.Elapsed.TotalSeconds, 2));
            Console.WriteLine("Average: {0}ms", Math.Round(stopwatchTimes.Average(time => time)));

            return stopwatchTimes;
        }, TaskCreationOptions.LongRunning);
    }

测试结果:

.NET 核心

• 平均:761 毫秒
• 总时长:38s

.NET 框架

• 平均:638 毫秒
• 总时长:32s

.NET Core 并不只在 CPU 相关任务上变慢。它在磁盘 I/O 任务上也较慢。

知道为什么 .NET Core 在这部分有点慢吗？我可以进行哪些更改来提高 .NET Core 的性能？

Answer 1

.NET Framework 项目默认为 32 位代码。此选项在项目的build设置中可见，默认情况下处于选中状态。 .NET Core 项目默认为 64 位代码。如果取消选中“首选 32 位”框，您会注意到 .NET Framework 的性能下降。

Another point of note is that the desktop x86 JIT is a separate code base from the x64 JIT. For 64-bit, both .NET Framework and .NET Core use RyuJIT now; for 32-bit .NET Core still uses RyuJIT, but .NET Framework uses the legacy JIT, so you've got both different bitness and a different jitter.

Hans Passant 和 Jeroen Mostert 在评论中提供了答案。