C#でランダムファイルの作成方法と読み込み速度計測ベンチマークテスト

using System;
using System.Diagnostics;
using System.IO;
using System.Threading.Tasks.Dataflow;

class Program
{
    const string FilePath = "test_random.dat";
    const int FileSizeMB = 100; // 作成するファイルサイズ（MB）
    const int BufferSize = 4 * 1024 * 1024; // 4MBのバッファで読み込み

    static void Main()
    {
        var sw = Stopwatch.StartNew();

        sw.Restart();
        DriveInfo[] drives = DriveInfo.GetDrives();
        foreach (DriveInfo drive in drives)
        {
            if (!drive.IsReady) continue;
            string path = Path.Join(drive.Name, FilePath);
            if (drive.Name == "C:\\")
            {
                path = Path.Join(Path.GetTempPath(), FilePath);
            }

            //Console.WriteLine("ランダムファイルを作成中...");
            CreateRandomFile(path, FileSizeMB);
            //Console.WriteLine("完了.");

            //Console.WriteLine("読み込み速度を計測中...");
            double result = BenchmarkRead(path);

            Console.WriteLine($"{Path.GetPathRoot(path)}  速度: {result:F2} MB/s");

            // 削除
            File.Delete(path);
        }
        sw.Stop();
        Console.WriteLine($"所要時間:{sw.ElapsedMilliseconds}ms");
    }

    static void CreateRandomFile(string path, int sizeMB)
    {
        var rand = new Random();
        byte[] buffer = new byte[BufferSize];
        using var fs = new FileStream(path, FileMode.Create, FileAccess.Write, FileShare.None);

        long bytesToWrite = sizeMB * 1024L * 1024L;
        while (bytesToWrite > 0)
        {
            rand.NextBytes(buffer);
            int writeSize = (int)Math.Min(buffer.Length, bytesToWrite);
            fs.Write(buffer, 0, writeSize);
            bytesToWrite -= writeSize;
        }
    }

    static double BenchmarkRead(string path)
    {
        byte[] buffer = new byte[BufferSize];
        Stopwatch sw = Stopwatch.StartNew();
        long totalBytesRead = 0;

        using var fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read);
        int bytesRead;
        while ((bytesRead = fs.Read(buffer, 0, buffer.Length)) > 0)
        {
            totalBytesRead += bytesRead;
        }

        sw.Stop();

        double seconds = sw.Elapsed.TotalSeconds;
        double mbRead = totalBytesRead / 1024.0 / 1024.0;
        double speedMBps = mbRead / seconds;

        //Console.WriteLine($"読み込み完了: {mbRead:F2} MB を {seconds:F2} 秒で読み込み。速度: {speedMBps:F2} MB/s");
        return speedMBps;
    }
}

C:\  速度: 5451.58 MB/s
D:\  速度: 5028.54 MB/s
E:\  速度: 5100.66 MB/s
F:\  速度: 5089.60 MB/s
G:\  速度: 5353.86 MB/s
X:\  速度: 230.20 MB/s
Y:\  速度: 223.41 MB/s
Z:\  速度: 227.88 MB/s
所要時間:3908ms