我正在尝试为我最近写的一些代码写一个测试，它通过分配GCHandle（用于与C++的互操作的持久使用）将内存标记为固定的。
我在一个包含一些float和int数组的单个对象中使用一个非常大的分配进行测试。我想检查一下，一旦我为每个数组释放了GCHandle，就可以对内存进行垃圾收集了。
目前，我可以看到分配的内存随着调用GC.GetTotalAllocatedBytes(true);或currentProcess.WorkingSet64;而增加，并且可以确认增加的大小与我对正在创建的对象的粗略估计（只是将对象中的大型数组的大小相加）相同。
然而，我似乎不能让数字在删除对象后缩小，即使没有固定上面的数组。我试过了

GC.Collect();            
GC.WaitForPendingFinalizers();

强制收集所有代的数据，但我的内存使用量从未下降。我知道GC可能会保留内存以供重用，但我希望有一种方法可以解除分配我为此目的而创建的大块内存。
我是不是看错了指标，还是这只是我无法控制的事情？
示例：

using System.Diagnostics;
using System.Runtime.InteropServices;

namespace TestApp
{
    public class MemUser
    {        
        private float[] data;
        private GCHandle dataHandle;
        public float[] Data { get { return data; } set { data = value; } }
        public MemUser(int numData)
        {
            data = new float[numData];
        }
        public long RoughSize()
        {
            return data.Length * sizeof(float);
        }
        public void GetPinnedHandles()
        {
            if (dataHandle.IsAllocated)
                dataHandle.Free();
            dataHandle = GCHandle.Alloc(dataHandle, GCHandleType.Pinned);
        }

        public void FreePinnedHandles()
        {
            if (dataHandle.IsAllocated)
                dataHandle.Free();
        }
        public void Clear()
        {
            FreePinnedHandles();
            data = null;
        }
    }

    public class Program
    {

        public static void Main(string[] args)
        {
            const int numFloats = 500 * 1000 * 1000;
            long beforeCreation = GetProcessMemory();
            // Create the object using a large chunk of memory 
            MemUser testMemory = new MemUser(numFloats);
            long roughMemSize = testMemory.RoughSize();
            // in practice, will pin the memory, but testing without for now
            //testMemory.GetPinnedHandles();

            //confirm memory in use jumps
            long afterCreation = GetProcessMemory();            
            long difference = afterCreation - beforeCreation;
            TestResult(difference, roughMemSize);

            // get rid of the object
            testMemory.Clear();
            testMemory = null;
           
            // this test fails, memory may have even gone up
            long afterDeletion = GetProcessMemory();
            difference = afterCreation - afterDeletion;
            TestResult(difference, roughMemSize);
        }

        public static long GetProcessMemory()
        {
            Process currentProcess = System.Diagnostics.Process.GetCurrentProcess();
            GC.Collect();
            GC.WaitForPendingFinalizers();
            long totalBytesOfMemoryUsed = GC.GetTotalAllocatedBytes(true);
            //long totalBytesOfMemoryUsed = currentProcess.WorkingSet64;
            return totalBytesOfMemoryUsed;
        }
        public static void TestResult(long difference, long expected)
        {
            
            if (difference >= expected)
                Console.Write($"PASS, difference ({difference}) >= {expected}\n");
            else
                Console.Write($"FAIL, difference ({difference}) < {expected}\n");
        }
    }
}