Byte buffer allocation benchmarks

BufferAllocation.cs

using System.Buffers;
using System.Runtime.InteropServices;
using BenchmarkDotNet.Attributes;

namespace MemoryBenchmarks
{
	[MemoryDiagnoser]
	public class BufferAllocation
	{
		private static readonly ArrayPool<byte> Pool = ArrayPool<byte>.Shared;

		[Params(32, 1024, 0xFFFF)]
		public int Size { get; set; }

		[Benchmark]
		public unsafe void NewByteArray()
		{
			var array = new byte[Size];
			fixed (byte* p = &array[0]) UseArray(p);
		}

		[Benchmark]
		public unsafe void PoolRentReturn()
		{
			var array = Pool.Rent(Size);
			fixed (byte* p = &array[0]) UseArray(p);
			Pool.Return(array);
		}

		[Benchmark]
		public unsafe void PoolRentReturnFinally()
		{
			var array = Pool.Rent(Size);
			try
			{
				fixed (byte* p = &array[0]) UseArray(p);
			}
			finally
			{
				Pool.Return(array);
			}
		}

		[Benchmark]
		public unsafe void AllocHGlobal()
		{
			var array = Marshal.AllocHGlobal(Size);
			UseArray((byte*)array.ToPointer());
			Marshal.FreeHGlobal(array);
		}

		[Benchmark]
		public unsafe void AllocHGlobalFinally()
		{
			var array = Marshal.AllocHGlobal(Size);
			try
			{
				UseArray((byte*)array.ToPointer());
			}
			finally
			{
				Marshal.FreeHGlobal(array);
			}
		}

		private unsafe void UseArray(byte* p)
		{
			*p = 0xAA;
			*(p + Size - 1) = 0x55;
		}
	}
}

Results.md

BenchmarkDotNet=v0.13.1, OS=Windows 10.0.19044.1586 (21H2) AMD Ryzen 5 3600, 1 CPU, 12 logical and 6 physical cores .NET SDK=6.0.201 [Host] : .NET 5.0.15 (5.0.1522.11506), X64 RyuJIT DefaultJob : .NET 5.0.15 (5.0.1522.11506), X64 RyuJIT

Method	Size	Mean	Error	StdDev	Gen 0	Allocated
NewByteArray	32	4.659 ns	0.0319 ns	0.0266 ns	0.0067	56 B
PoolRentReturn	32	22.006 ns	0.4623 ns	0.6777 ns	-	-
PoolRentReturnFinally	32	23.569 ns	0.3503 ns	0.3277 ns	-	-
AllocHGlobal	32	74.074 ns	0.8751 ns	0.8185 ns	-	-
AllocHGlobalFinally	32	77.727 ns	1.4962 ns	1.4694 ns	-	-
NewByteArray	1024	30.218 ns	0.6332 ns	0.5923 ns	0.1253	1,048 B
PoolRentReturn	1024	21.499 ns	0.0950 ns	0.0888 ns	-	-
PoolRentReturnFinally	1024	23.395 ns	0.1559 ns	0.1382 ns	-	-
AllocHGlobal	1024	74.174 ns	1.3297 ns	1.1787 ns	-	-
AllocHGlobalFinally	1024	75.901 ns	0.1468 ns	0.1146 ns	-	-
NewByteArray	65535	1,260.709 ns	1.4556 ns	1.1365 ns	7.8106	65,560 B
PoolRentReturn	65535	21.500 ns	0.0299 ns	0.0265 ns	-	-
PoolRentReturnFinally	65535	23.350 ns	0.1060 ns	0.0991 ns	-	-
AllocHGlobal	65535	142.286 ns	2.2879 ns	1.7862 ns	-	-
AllocHGlobalFinally	65535	151.852 ns	3.0494 ns	3.2628 ns	-	-