C#内存复制性能分析

    static class Program
    {
        [DllImport("kernel32.dll", EntryPoint = "CopyMemory", SetLastError = false)]
        public static extern void CopyMemory(IntPtr dest, IntPtr src, uint count);

        /// <summary>
        /// 应用程序的主入口点。
        /// </summary>
        [STAThread]
        static void Main()
        {
            LogStopwatch stopwatch = new LogStopwatch("内存操作");
            int size = 1024 * 1024 * 1024;
            byte[] data1 = new byte[size];
            byte[] data2 = new byte[size];
            stopwatch.Peek("分配");

            for(int l = 0; l < size; l++)
            {
                data1[l] = (byte)(l & 0xFF);
            }
            stopwatch.Peek("赋值");

            Array.Copy(data1, data2, data1.Length);
            stopwatch.Peek("Array.Copy: byte[] -> byte[]");

            Array.ConstrainedCopy(data1, 0, data2, 0, data1.Length);
            stopwatch.Peek("Array.ConstrainedCopy: byte[] -> byte[]");

            Buffer.BlockCopy(data1, 0, data2, 0, data2.Length);
            stopwatch.Peek("Buffer.BlockCopy: byte[] -> byte[]");

            IntPtr dest1 = Marshal.AllocHGlobal(size);
            IntPtr dest2 = Marshal.AllocHGlobal(size);
            stopwatch.Peek("Marshal.AllocHGlobal");

            Marshal.Copy(data1, 0, dest1, data1.Length);
            stopwatch.Peek("Marshal.Copy: byte[] -> IntPtr");

            CopyMemory(dest2, dest1, (uint)size);
            stopwatch.Peek("CopyMemory: IntPtr -> IntPtr");

            Marshal.Copy(dest2, data2, 0, data2.Length);
            stopwatch.Peek("Marshal.Copy: IntPtr -> byte[]");
        }
    }

 

12:11:46.9739 [INFO] 内存操作:开始 [0ms]
12:11:46.9999 [INFO] 内存操作:分配 [3->3ms]
12:11:47.5391 [INFO] 内存操作:赋值 [539->542ms]
12:11:47.8350 [INFO] 内存操作:Array.Copy: byte[] -> byte[] [296->838ms]
12:11:47.9069 [INFO] 内存操作:Array.ConstrainedCopy: byte[] -> byte[] [72->910ms]
12:11:47.9762 [INFO] 内存操作:Buffer.BlockCopy: byte[] -> byte[] [69->979ms]
12:11:47.9762 [INFO] 内存操作:Marshal.AllocHGlobal [0->979ms]
12:11:48.1528 [INFO] 内存操作:Marshal.Copy: byte[] -> IntPtr [177->1156ms]
12:11:48.3209 [INFO] 内存操作:CopyMemory: IntPtr -> IntPtr [168->1324ms]
12:11:48.3996 [INFO] 内存操作:Marshal.Copy: IntPtr -> byte[] [78->1402ms]

1G内存复制，最快的方式是：Buffer.BlockCopy: byte[] -> byte[], Marshal.Copy: IntPtr -> byte[]，大约用时七八十毫秒