Reducing memory allocations (#4537)

* add RecyclableMemoryStream dependency and MemoryStreamManager

* organize BinaryReader/BinaryWriter extensions

* add StreamExtensions to reduce need for BinaryWriter

* simple replacments of MemoryStream with RecyclableMemoryStream

* add write ReadOnlySequence<byte> support to IVirtualMemoryManager

* avoid 0-length array creation

* rework IpcMessage and related types to greatly reduce memory allocation by using RecylableMemoryStream, keeping streams around longer, avoiding their creation when possible, and avoiding creation of BinaryReader and BinaryWriter when possible

* reduce LINQ-induced memory allocations with custom methods to query KPriorityQueue

* use RecyclableMemoryStream in StreamUtils, and use StreamUtils in EmbeddedResources

* add constants for nanosecond/millisecond conversions

* code formatting

* XML doc adjustments

* fix: StreamExtension.WriteByte not writing non-zero values for lengths <= 16

* XML Doc improvements. Implement StreamExtensions.WriteByte() block writes for large-enough count values.

* add copyless path for StreamExtension.Write(ReadOnlySpan<int>)

* add default implementation of IVirtualMemoryManager.Write(ulong, ReadOnlySequence<byte>); remove previous explicit implementations

* code style fixes

* remove LINQ completely from KScheduler/KPriorityQueue by implementing a custom struct-based enumerator

ARMeilleure/CodeGen/Arm64/CodeGenContext.cs

@@ -1,6 +1,7 @@
 using ARMeilleure.CodeGen.Linking;
 using ARMeilleure.CodeGen.RegisterAllocators;
 using ARMeilleure.IntermediateRepresentation;
+using Ryujinx.Common.Memory;
 using System;
 using System.Collections.Generic;
 using System.IO;
@@ -59,7 +60,7 @@ namespace ARMeilleure.CodeGen.Arm64
 
         public CodeGenContext(AllocationResult allocResult, int maxCallArgs, int blocksCount, bool relocatable)
         {
-            _stream = new MemoryStream();
+            _stream = MemoryStreamManager.Shared.GetStream();
 
             AllocResult = allocResult;
 

ARMeilleure/CodeGen/X86/Assembler.cs

@@ -1,5 +1,6 @@
 using ARMeilleure.CodeGen.Linking;
 using ARMeilleure.IntermediateRepresentation;
+using Ryujinx.Common.Memory;
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
@@ -1285,7 +1286,7 @@ namespace ARMeilleure.CodeGen.X86
             // Write the code, ignoring the dummy bytes after jumps, into a new stream.
             _stream.Seek(0, SeekOrigin.Begin);
 
-            using var codeStream = new MemoryStream();
+            using var codeStream = MemoryStreamManager.Shared.GetStream();
             var assembler = new Assembler(codeStream, HasRelocs);
 
             bool hasRelocs = HasRelocs;

ARMeilleure/CodeGen/X86/CodeGenContext.cs

@@ -1,5 +1,6 @@
 using ARMeilleure.CodeGen.RegisterAllocators;
 using ARMeilleure.IntermediateRepresentation;
+using Ryujinx.Common.Memory;
 using System.IO;
 using System.Numerics;
 
@@ -22,7 +23,7 @@ namespace ARMeilleure.CodeGen.X86
 
         public CodeGenContext(AllocationResult allocResult, int maxCallArgs, int blocksCount, bool relocatable)
         {
-            _stream = new MemoryStream();
+            _stream = MemoryStreamManager.Shared.GetStream();
             _blockLabels = new Operand[blocksCount];
 
             AllocResult = allocResult;

ARMeilleure/Translation/PTC/Ptc.cs

@@ -6,6 +6,7 @@ using ARMeilleure.Memory;
 using Ryujinx.Common;
 using Ryujinx.Common.Configuration;
 using Ryujinx.Common.Logging;
+using Ryujinx.Common.Memory;
 using System;
 using System.Buffers.Binary;
 using System.Collections.Generic;
@@ -150,10 +151,10 @@ namespace ARMeilleure.Translation.PTC
 
         private void InitializeCarriers()
         {
-            _infosStream = new MemoryStream();
+            _infosStream = MemoryStreamManager.Shared.GetStream();
             _codesList = new List<byte[]>();
-            _relocsStream = new MemoryStream();
+            _relocsStream = MemoryStreamManager.Shared.GetStream();
-            _unwindInfosStream = new MemoryStream();
+            _unwindInfosStream = MemoryStreamManager.Shared.GetStream();
         }
 
         private void DisposeCarriers()

ARMeilleure/Translation/PTC/PtcProfiler.cs

@@ -1,6 +1,7 @@
 using ARMeilleure.State;
 using Ryujinx.Common;
 using Ryujinx.Common.Logging;
+using Ryujinx.Common.Memory;
 using System;
 using System.Buffers.Binary;
 using System.Collections.Concurrent;
@@ -182,7 +183,7 @@ namespace ARMeilleure.Translation.PTC
                     return false;
                 }
 
-                using (MemoryStream stream = new MemoryStream())
+                using (MemoryStream stream = MemoryStreamManager.Shared.GetStream())
                 {
                     Debug.Assert(stream.Seek(0L, SeekOrigin.Begin) == 0L && stream.Length == 0L);
 
@@ -274,7 +275,7 @@ namespace ARMeilleure.Translation.PTC
 
             outerHeader.SetHeaderHash();
 
-            using (MemoryStream stream = new MemoryStream())
+            using (MemoryStream stream = MemoryStreamManager.Shared.GetStream())
             {
                 Debug.Assert(stream.Seek(0L, SeekOrigin.Begin) == 0L && stream.Length == 0L);
 

Directory.Packages.props

@@ -22,6 +22,7 @@
     <PackageVersion Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.4" />
     <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="4.5.0" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.5.0" />
+    <PackageVersion Include="Microsoft.IO.RecyclableMemoryStream" Version="2.3.2" />
     <PackageVersion Include="MsgPack.Cli" Version="1.0.1" />
     <PackageVersion Include="NUnit" Version="3.13.3" />
     <PackageVersion Include="NUnit3TestAdapter" Version="4.1.0" />

Ryujinx.Common/Extensions/BinaryReaderExtensions.cs

@@ -12,19 +12,5 @@ namespace Ryujinx.Common
         {
             return MemoryMarshal.Cast<byte, T>(reader.ReadBytes(Unsafe.SizeOf<T>()))[0];
         }
-
-        public unsafe static void WriteStruct<T>(this BinaryWriter writer, T value)
-            where T : unmanaged
-        {
-            ReadOnlySpan<byte> data = MemoryMarshal.Cast<T, byte>(MemoryMarshal.CreateReadOnlySpan(ref value, 1));
-
-            writer.Write(data);
-        }
-
-        public static void Write(this BinaryWriter writer, UInt128 value)
-        {
-            writer.Write((ulong)value);
-            writer.Write((ulong)(value >> 64));
-        }
     }
 }

Ryujinx.Common/Extensions/BinaryWriterExtensions.cs

@@ -0,0 +1,28 @@
+using System;
+using System.IO;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.Common
+{
+    public static class BinaryWriterExtensions
+    {
+        public unsafe static void WriteStruct<T>(this BinaryWriter writer, T value)
+            where T : unmanaged
+        {
+            ReadOnlySpan<byte> data = MemoryMarshal.Cast<T, byte>(MemoryMarshal.CreateReadOnlySpan(ref value, 1));
+
+            writer.Write(data);
+        }
+
+        public static void Write(this BinaryWriter writer, UInt128 value)
+        {
+            writer.Write((ulong)value);
+            writer.Write((ulong)(value >> 64));
+        }
+
+        public static void Write(this BinaryWriter writer, MemoryStream stream)
+        {
+            stream.CopyTo(writer.BaseStream);
+        }
+    }
+}

Ryujinx.Common/Extensions/StreamExtensions.cs

@@ -0,0 +1,138 @@
+using System;
+using System.Buffers.Binary;
+using System.IO;
+using System.Runtime.InteropServices;
+
+namespace Ryujinx.Common
+{
+    public static class StreamExtensions
+    {
+        /// <summary>
+        /// Writes a <cref="ReadOnlySpan<int>" /> to this stream.
+        ///
+        /// This default implementation converts each buffer value to a stack-allocated
+        /// byte array, then writes it to the Stream using <cref="System.Stream.Write(byte[])" />.
+        /// </summary>
+        /// <param name="stream">The stream to be written to</param>
+        /// <param name="buffer">The buffer of values to be written</param>
+        public static void Write(this Stream stream, ReadOnlySpan<int> buffer)
+        {
+            if (buffer.Length == 0)
+            {
+                return;
+            }
+
+            if (BitConverter.IsLittleEndian)
+            {
+                ReadOnlySpan<byte> byteBuffer = MemoryMarshal.Cast<int, byte>(buffer);
+                stream.Write(byteBuffer);
+            }
+            else
+            {
+                Span<byte> byteBuffer = stackalloc byte[sizeof(int)];
+
+                foreach (int value in buffer)
+                {
+                    BinaryPrimitives.WriteInt32LittleEndian(byteBuffer, value);
+                    stream.Write(byteBuffer);
+                }
+            }
+        }
+
+        /// <summary>
+        /// Writes a four-byte signed integer to this stream. The current position
+        /// of the stream is advanced by four.
+        /// </summary>
+        /// <param name="stream">The stream to be written to</param>
+        /// <param name="value">The value to be written</param>
+        public static void Write(this Stream stream, int value)
+        {
+            Span<byte> buffer = stackalloc byte[sizeof(int)];
+            BinaryPrimitives.WriteInt32LittleEndian(buffer, value);
+            stream.Write(buffer);
+        }
+
+        /// <summary>
+        /// Writes an eight-byte signed integer to this stream. The current position
+        /// of the stream is advanced by eight.
+        /// </summary>
+        /// <param name="stream">The stream to be written to</param>
+        /// <param name="value">The value to be written</param>
+        public static void Write(this Stream stream, long value)
+        {
+            Span<byte> buffer = stackalloc byte[sizeof(long)];
+            BinaryPrimitives.WriteInt64LittleEndian(buffer, value);
+            stream.Write(buffer);
+        }
+
+        /// <summary>
+        // Writes a four-byte unsigned integer to this stream. The current position
+        // of the stream is advanced by four.
+        /// </summary>
+        /// <param name="stream">The stream to be written to</param>
+        /// <param name="value">The value to be written</param>
+        public static void Write(this Stream stream, uint value)
+        {
+            Span<byte> buffer = stackalloc byte[sizeof(uint)];
+            BinaryPrimitives.WriteUInt32LittleEndian(buffer, value);
+            stream.Write(buffer);
+        }
+
+        /// <summary>
+        /// Writes an eight-byte unsigned integer to this stream. The current
+        /// position of the stream is advanced by eight.
+        /// </summary>
+        /// <param name="stream">The stream to be written to</param>
+        /// <param name="value">The value to be written</param>
+        public static void Write(this Stream stream, ulong value)
+        {
+            Span<byte> buffer = stackalloc byte[sizeof(ulong)];
+            BinaryPrimitives.WriteUInt64LittleEndian(buffer, value);
+            stream.Write(buffer);
+        }
+
+        /// <summary>
+        /// Writes the contents of source to stream by calling source.CopyTo(stream).
+        /// Provides consistency with other Stream.Write methods.
+        /// </summary>
+        /// <param name="stream">The stream to be written to</param>
+        /// <param name="source">The stream to be read from</param>
+        public static void Write(this Stream stream, Stream source)
+        {
+            source.CopyTo(stream);
+        }
+
+        /// <summary>
+        /// Writes a sequence of bytes to the Stream.
+        /// </summary>
+        /// <param name="stream">The stream to be written to.</param>
+        /// <param name="value">The byte to be written</param>
+        /// <param name="count">The number of times the value should be written</param>
+        public static void WriteByte(this Stream stream, byte value, int count)
+        {
+            if (count <= 0)
+            {
+                return;
+            }
+
+            const int BlockSize = 16;
+
+            int blockCount = count / BlockSize;
+            if (blockCount > 0)
+            {
+                Span<byte> span = stackalloc byte[BlockSize];
+                span.Fill(value);
+                for (int x = 0; x < blockCount; x++)
+                {
+                    stream.Write(span);
+                }
+            }
+
+            int nonBlockBytes = count % BlockSize;
+            for (int x = 0; x < nonBlockBytes; x++)
+            {
+                stream.WriteByte(value);
+            }
+        }
+    }
+}

Ryujinx.Common/Memory/MemoryStreamManager.cs

@@ -0,0 +1,99 @@
+using Microsoft.IO;
+using System;
+
+namespace Ryujinx.Common.Memory
+{
+    public static class MemoryStreamManager
+    {
+        private static readonly RecyclableMemoryStreamManager _shared = new RecyclableMemoryStreamManager();
+
+        /// <summary>
+        /// We don't expose the <c>RecyclableMemoryStreamManager</c> directly because version 2.x
+        /// returns them as <c>MemoryStream</c>. This Shared class is here to a) offer only the GetStream() versions we use
+        /// and b) return them as <c>RecyclableMemoryStream</c> so we don't have to cast.
+        /// </summary>
+        public static class Shared
+        {
+            /// <summary>
+            /// Retrieve a new <c>MemoryStream</c> object with no tag and a default initial capacity.
+            /// </summary>
+            /// <returns>A <c>RecyclableMemoryStream</c></returns>
+            public static RecyclableMemoryStream GetStream()
+                => new RecyclableMemoryStream(_shared);
+
+            /// <summary>
+            /// Retrieve a new <c>MemoryStream</c> object with the contents copied from the provided
+            /// buffer. The provided buffer is not wrapped or used after construction.
+            /// </summary>
+            /// <remarks>The new stream's position is set to the beginning of the stream when returned.</remarks>
+            /// <param name="buffer">The byte buffer to copy data from</param>
+            /// <returns>A <c>RecyclableMemoryStream</c></returns>
+            public static RecyclableMemoryStream GetStream(byte[] buffer)
+                => GetStream(Guid.NewGuid(), null, buffer, 0, buffer.Length);
+
+            /// <summary>
+            /// Retrieve a new <c>MemoryStream</c> object with the given tag and with contents copied from the provided
+            /// buffer. The provided buffer is not wrapped or used after construction.
+            /// </summary>
+            /// <remarks>The new stream's position is set to the beginning of the stream when returned.</remarks>
+            /// <param name="buffer">The byte buffer to copy data from</param>
+            /// <returns>A <c>RecyclableMemoryStream</c></returns>
+            public static RecyclableMemoryStream GetStream(ReadOnlySpan<byte> buffer)
+                => GetStream(Guid.NewGuid(), null, buffer);
+
+            /// <summary>
+            /// Retrieve a new <c>RecyclableMemoryStream</c> object with the given tag and with contents copied from the provided
+            /// buffer. The provided buffer is not wrapped or used after construction.
+            /// </summary>
+            /// <remarks>The new stream's position is set to the beginning of the stream when returned.</remarks>
+            /// <param name="id">A unique identifier which can be used to trace usages of the stream</param>
+            /// <param name="tag">A tag which can be used to track the source of the stream</param>
+            /// <param name="buffer">The byte buffer to copy data from</param>
+            /// <returns>A <c>RecyclableMemoryStream</c></returns>
+            public static RecyclableMemoryStream GetStream(Guid id, string tag, ReadOnlySpan<byte> buffer)
+            {
+                RecyclableMemoryStream stream = null;
+                try
+                {
+                    stream = new RecyclableMemoryStream(_shared, id, tag, buffer.Length);
+                    stream.Write(buffer);
+                    stream.Position = 0;
+                    return stream;
+                }
+                catch
+                {
+                    stream?.Dispose();
+                    throw;
+                }
+            }
+
+            /// <summary>
+            /// Retrieve a new <c>RecyclableMemoryStream</c> object with the given tag and with contents copied from the provided
+            /// buffer. The provided buffer is not wrapped or used after construction.
+            /// </summary>
+            /// <remarks>The new stream's position is set to the beginning of the stream when returned</remarks>
+            /// <param name="id">A unique identifier which can be used to trace usages of the stream</param>
+            /// <param name="tag">A tag which can be used to track the source of the stream</param>
+            /// <param name="buffer">The byte buffer to copy data from</param>
+            /// <param name="offset">The offset from the start of the buffer to copy from</param>
+            /// <param name="count">The number of bytes to copy from the buffer</param>
+            /// <returns>A <c>RecyclableMemoryStream</c></returns>
+            public static RecyclableMemoryStream GetStream(Guid id, string tag, byte[] buffer, int offset, int count)
+            {
+                RecyclableMemoryStream stream = null;
+                try
+                {
+                    stream = new RecyclableMemoryStream(_shared, id, tag, count);
+                    stream.Write(buffer, offset, count);
+                    stream.Position = 0;
+                    return stream;
+                }
+                catch
+                {
+                    stream?.Dispose();
+                    throw;
+                }
+            }
+        }
+    }
+}

Ryujinx.Common/Ryujinx.Common.csproj

@@ -7,6 +7,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.IO.RecyclableMemoryStream" />
     <PackageReference Include="MsgPack.Cli" />
     <PackageReference Include="System.Management" />
   </ItemGroup>

Ryujinx.Common/Utilities/EmbeddedResources.cs

@@ -1,3 +1,5 @@
+using Ryujinx.Common.Memory;
+using Ryujinx.Common.Utilities;
 using System;
 using System.IO;
 using System.Linq;
@@ -38,12 +40,7 @@ namespace Ryujinx.Common
                     return null;
                 }
 
-                using (var mem = new MemoryStream())
+                return StreamUtils.StreamToBytes(stream);
-                {
-                    stream.CopyTo(mem);
-
-                    return mem.ToArray();
-                }
             }
         }
 
@@ -56,12 +53,7 @@ namespace Ryujinx.Common
                     return null;
                 }
 
-                using (var mem = new MemoryStream())
+                return await StreamUtils.StreamToBytesAsync(stream);
-                {
-                    await stream.CopyToAsync(mem);
-
-                    return mem.ToArray();
-                }
             }
         }
 

Ryujinx.Common/Utilities/StreamUtils.cs

@@ -1,4 +1,8 @@
-using System.IO;
+using Microsoft.IO;
+using Ryujinx.Common.Memory;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
 
 namespace Ryujinx.Common.Utilities
 {
@@ -6,12 +10,22 @@ namespace Ryujinx.Common.Utilities
     {
         public static byte[] StreamToBytes(Stream input)
         {
-            using (MemoryStream stream = new MemoryStream())
+            using (MemoryStream stream = MemoryStreamManager.Shared.GetStream())
             {
                 input.CopyTo(stream);
 
                 return stream.ToArray();
             }
         }
+
+        public static async Task<byte[]> StreamToBytesAsync(Stream input, CancellationToken cancellationToken = default)
+        {
+            using (MemoryStream stream = MemoryStreamManager.Shared.GetStream())
+            {
+                await input.CopyToAsync(stream, cancellationToken);
+
+                return stream.ToArray();
+            }
+        }
     }
 }

Ryujinx.Cpu/MemoryHelper.cs

@@ -1,4 +1,6 @@
-using Ryujinx.Memory;
+using Microsoft.IO;
+using Ryujinx.Common.Memory;
+using Ryujinx.Memory;
 using System;
 using System.IO;
 using System.Runtime.CompilerServices;
@@ -40,7 +42,7 @@ namespace Ryujinx.Cpu
 
         public static string ReadAsciiString(IVirtualMemoryManager memory, ulong position, long maxSize = -1)
         {
-            using (MemoryStream ms = new MemoryStream())
+            using (RecyclableMemoryStream ms = MemoryStreamManager.Shared.GetStream())
             {
                 for (long offs = 0; offs < maxSize || maxSize == -1; offs++)
                 {
@@ -54,7 +56,7 @@ namespace Ryujinx.Cpu
                     ms.WriteByte(value);
                 }
 
-                return Encoding.ASCII.GetString(ms.ToArray());
+                return Encoding.ASCII.GetString(ms.GetReadOnlySequence());
             }
         }
     }

Ryujinx.Graphics.Gpu/Shader/DiskCache/ShaderBinarySerializer.cs

@@ -1,3 +1,5 @@
+using Ryujinx.Common;
+using Ryujinx.Common.Memory;
 using Ryujinx.Graphics.GAL;
 using Ryujinx.Graphics.Shader;
 using Ryujinx.Graphics.Shader.Translation;
@@ -11,16 +13,15 @@ namespace Ryujinx.Graphics.Gpu.Shader.DiskCache
     {
         public static byte[] Pack(ShaderSource[] sources)
         {
-            using MemoryStream output = new MemoryStream();
+            using MemoryStream output = MemoryStreamManager.Shared.GetStream();
-            using BinaryWriter writer = new BinaryWriter(output);
 
-            writer.Write(sources.Length);
+            output.Write(sources.Length);
 
-            for (int i = 0; i < sources.Length; i++)
+            foreach (ShaderSource source in sources)
             {
-                writer.Write((int)sources[i].Stage);
+                output.Write((int)source.Stage);
-                writer.Write(sources[i].BinaryCode.Length);
+                output.Write(source.BinaryCode.Length);
-                writer.Write(sources[i].BinaryCode);
+                output.Write(source.BinaryCode);
             }
 
             return output.ToArray();

Ryujinx.HLE/FileSystem/ContentManager.cs

@@ -9,6 +9,7 @@ using LibHac.Tools.FsSystem;
 using LibHac.Tools.FsSystem.NcaUtils;
 using LibHac.Tools.Ncm;
 using Ryujinx.Common.Logging;
+using Ryujinx.Common.Memory;
 using Ryujinx.Common.Utilities;
 using Ryujinx.HLE.Exceptions;
 using Ryujinx.HLE.HOS.Services.Ssl;
@@ -637,12 +638,12 @@ namespace Ryujinx.HLE.FileSystem
 
         private Stream GetZipStream(ZipArchiveEntry entry)
         {
-            MemoryStream dest = new MemoryStream();
+            MemoryStream dest = MemoryStreamManager.Shared.GetStream();
-
-            Stream src = entry.Open();
 
+            using (Stream src = entry.Open())
+            {
                 src.CopyTo(dest);
-            src.Dispose();
+            }
 
             return dest;
         }

Ryujinx.HLE/HOS/Applets/Browser/BrowserApplet.cs

@@ -1,5 +1,6 @@
 using Ryujinx.Common;
 using Ryujinx.Common.Logging;
+using Ryujinx.Common.Memory;
 using Ryujinx.HLE.HOS.Services.Am.AppletAE;
 using System;
 using System.Collections.Generic;
@@ -70,7 +71,7 @@ namespace Ryujinx.HLE.HOS.Applets.Browser
 
         private byte[] BuildResponseOld(WebCommonReturnValue result)
         {
-            using (MemoryStream stream = new MemoryStream())
+            using (MemoryStream stream = MemoryStreamManager.Shared.GetStream())
             using (BinaryWriter writer = new BinaryWriter(stream))
             {
                 writer.WriteStruct(result);
@@ -80,7 +81,7 @@ namespace Ryujinx.HLE.HOS.Applets.Browser
         }
         private byte[] BuildResponseNew(List<BrowserOutput> outputArguments)
         {
-            using (MemoryStream stream = new MemoryStream())
+            using (MemoryStream stream = MemoryStreamManager.Shared.GetStream())
             using (BinaryWriter writer = new BinaryWriter(stream))
             {
                 writer.WriteStruct(new WebArgHeader

Ryujinx.HLE/HOS/Applets/Controller/ControllerApplet.cs

@@ -1,4 +1,5 @@
 using Ryujinx.Common.Logging;
+using Ryujinx.Common.Memory;
 using Ryujinx.HLE.HOS.Services.Am.AppletAE;
 using Ryujinx.HLE.HOS.Services.Hid;
 using Ryujinx.HLE.HOS.Services.Hid.Types;
@@ -123,7 +124,7 @@ namespace Ryujinx.HLE.HOS.Applets
 
         private byte[] BuildResponse(ControllerSupportResultInfo result)
         {
-            using (MemoryStream stream = new MemoryStream())
+            using (MemoryStream stream = MemoryStreamManager.Shared.GetStream())
             using (BinaryWriter writer = new BinaryWriter(stream))
             {
                 writer.Write(MemoryMarshal.AsBytes(MemoryMarshal.CreateReadOnlySpan(ref result, Unsafe.SizeOf<ControllerSupportResultInfo>())));
@@ -134,7 +135,7 @@ namespace Ryujinx.HLE.HOS.Applets
 
         private byte[] BuildResponse()
         {
-            using (MemoryStream stream = new MemoryStream())
+            using (MemoryStream stream = MemoryStreamManager.Shared.GetStream())
             using (BinaryWriter writer = new BinaryWriter(stream))
             {
                 writer.Write((ulong)ResultCode.Success);

Ryujinx.HLE/HOS/Applets/PlayerSelect/PlayerSelectApplet.cs

@@ -1,4 +1,5 @@
-using Ryujinx.HLE.HOS.Services.Account.Acc;
+using Ryujinx.Common.Memory;
+using Ryujinx.HLE.HOS.Services.Account.Acc;
 using Ryujinx.HLE.HOS.Services.Am.AppletAE;
 using System;
 using System.IO;
@@ -43,7 +44,7 @@ namespace Ryujinx.HLE.HOS.Applets
         {
             UserProfile currentUser = _system.AccountManager.LastOpenedUser;
 
-            using (MemoryStream stream = new MemoryStream())
+            using (MemoryStream stream = MemoryStreamManager.Shared.GetStream())
             using (BinaryWriter writer = new BinaryWriter(stream))
             {
                 writer.Write((ulong)PlayerSelectResult.Success);

Ryujinx.HLE/HOS/Ipc/IpcHandleDesc.cs

@@ -1,3 +1,6 @@
+using Microsoft.IO;
+using Ryujinx.Common;
+using Ryujinx.Common.Memory;
 using System;
 using System.IO;
 
@@ -18,20 +21,27 @@ namespace Ryujinx.HLE.HOS.Ipc
 
             HasPId = (word & 1) != 0;
 
-            ToCopy = new int[(word >> 1) & 0xf];
-            ToMove = new int[(word >> 5) & 0xf];
-
             PId = HasPId ? reader.ReadUInt64() : 0;
 
-            for (int index = 0; index < ToCopy.Length; index++)
+            int toCopySize = (word >> 1) & 0xf;
+            int[] toCopy = toCopySize == 0 ? Array.Empty<int>() : new int[toCopySize];
+
+            for (int index = 0; index < toCopy.Length; index++)
             {
-                ToCopy[index] = reader.ReadInt32();
+                toCopy[index] = reader.ReadInt32();
             }
 
-            for (int index = 0; index < ToMove.Length; index++)
+            ToCopy = toCopy;
+
+            int toMoveSize = (word >> 5) & 0xf;
+            int[] toMove = toMoveSize == 0 ? Array.Empty<int>() : new int[toMoveSize];
+
+            for (int index = 0; index < toMove.Length; index++)
             {
-                ToMove[index] = reader.ReadInt32();
+                toMove[index] = reader.ReadInt32();
             }
+
+            ToMove = toMove;
         }
 
         public IpcHandleDesc(int[] copy, int[] move)
@@ -57,36 +67,27 @@ namespace Ryujinx.HLE.HOS.Ipc
             return new IpcHandleDesc(Array.Empty<int>(), handles);
         }
 
-        public byte[] GetBytes()
+        public RecyclableMemoryStream GetStream()
         {
-            using (MemoryStream ms = new MemoryStream())
+            RecyclableMemoryStream ms = MemoryStreamManager.Shared.GetStream();
-            {
-                BinaryWriter writer = new BinaryWriter(ms);
 
             int word = HasPId ? 1 : 0;
 
             word |= (ToCopy.Length & 0xf) << 1;
             word |= (ToMove.Length & 0xf) << 5;
 
-                writer.Write(word);
+            ms.Write(word);
 
             if (HasPId)
             {
-                    writer.Write(PId);
+                ms.Write(PId);
             }
 
-                foreach (int handle in ToCopy)
+            ms.Write(ToCopy);
-                {
+            ms.Write(ToMove);
-                    writer.Write(handle);
-                }
 
-                foreach (int handle in ToMove)
+            ms.Position = 0;
-                {
+            return ms;
-                    writer.Write(handle);
-                }
-
-                return ms.ToArray();
-            }
         }
     }
 }

Ryujinx.HLE/HOS/Ipc/IpcMessage.cs

@@ -1,4 +1,8 @@
+using Microsoft.IO;
+using Ryujinx.Common;
+using Ryujinx.Common.Memory;
 using System;
+using System.Buffers;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
@@ -32,9 +36,9 @@ namespace Ryujinx.HLE.HOS.Ipc
             ObjectIds = new List<int>();
         }
 
-        public IpcMessage(byte[] data, long cmdPtr) : this()
+        public IpcMessage(ReadOnlySpan<byte> data, long cmdPtr) : this()
         {
-            using (MemoryStream ms = new MemoryStream(data))
+            using (RecyclableMemoryStream ms = MemoryStreamManager.Shared.GetStream(data))
             {
                 BinaryReader reader = new BinaryReader(ms);
 
@@ -114,15 +118,13 @@ namespace Ryujinx.HLE.HOS.Ipc
 
             for (int index = 0; index < recvListCount; index++)
             {
-                RecvListBuff.Add(new IpcRecvListBuffDesc(reader));
+                RecvListBuff.Add(new IpcRecvListBuffDesc(reader.ReadUInt64()));
             }
         }
 
-        public byte[] GetBytes(long cmdPtr, ulong recvListAddr)
+        public RecyclableMemoryStream GetStream(long cmdPtr, ulong recvListAddr)
         {
-            using (MemoryStream ms = new MemoryStream())
+            RecyclableMemoryStream ms = MemoryStreamManager.Shared.GetStream();
-            {
-                BinaryWriter writer = new BinaryWriter(ms);
 
             int word0;
             int word1;
@@ -133,12 +135,7 @@ namespace Ryujinx.HLE.HOS.Ipc
             word0 |= (ReceiveBuff.Count  & 0xf) << 24;
             word0 |= (ExchangeBuff.Count & 0xf) << 28;
 
-                byte[] handleData = Array.Empty<byte>();
+            using RecyclableMemoryStream handleDataStream = HandleDesc?.GetStream();
-
-                if (HandleDesc != null)
-                {
-                    handleData = HandleDesc.GetBytes();
-                }
 
             int dataLength = RawData?.Length ?? 0;
 
@@ -146,7 +143,7 @@ namespace Ryujinx.HLE.HOS.Ipc
 
             int rawLength = dataLength;
 
-                int pad0 = (int)GetPadSize16(cmdPtr + 8 + handleData.Length + PtrBuff.Count * 8);
+            int pad0 = (int)GetPadSize16(cmdPtr + 8 + (handleDataStream?.Length ?? 0) + PtrBuff.Count * 8);
 
             // Apparently, padding after Raw Data is 16 bytes, however when there is
             // padding before Raw Data too, we need to subtract the size of this padding.
@@ -162,38 +159,42 @@ namespace Ryujinx.HLE.HOS.Ipc
                 word1 |= 1 << 31;
             }
 
-                writer.Write(word0);
+            ms.Write(word0);
-                writer.Write(word1);
+            ms.Write(word1);
-                writer.Write(handleData);
 
-                for (int index = 0; index < PtrBuff.Count; index++)
+            if (handleDataStream != null)
             {
-                    writer.Write(PtrBuff[index].GetWord0());
+                ms.Write(handleDataStream);
-                    writer.Write(PtrBuff[index].GetWord1());
             }
 
-                ms.Seek(pad0, SeekOrigin.Current);
+            foreach (IpcPtrBuffDesc ptrBuffDesc in PtrBuff)
+            {
+                ms.Write(ptrBuffDesc.GetWord0());
+                ms.Write(ptrBuffDesc.GetWord1());
+            }
+
+            ms.WriteByte(0, pad0);
 
             if (RawData != null)
             {
-                    writer.Write(RawData);
+                ms.Write(RawData);
-                    ms.Seek(rawLength - RawData.Length, SeekOrigin.Current);
+                ms.WriteByte(0, rawLength - RawData.Length);
             }
 
-                writer.Write(new byte[pad1]);
+            ms.WriteByte(0, pad1);
-                writer.Write(recvListAddr);
 
-                return ms.ToArray();
+            ms.Write(recvListAddr);
-            }
+
+            ms.Position = 0;
+
+            return ms;
         }
 
-        public byte[] GetBytesTipc()
+        public RecyclableMemoryStream GetStreamTipc()
         {
             Debug.Assert(PtrBuff.Count == 0);
 
-            using (MemoryStream ms = new MemoryStream())
+            RecyclableMemoryStream ms = MemoryStreamManager.Shared.GetStream();
-            {
-                BinaryWriter writer = new BinaryWriter(ms);
 
             int word0;
             int word1;
@@ -203,12 +204,7 @@ namespace Ryujinx.HLE.HOS.Ipc
             word0 |= (ReceiveBuff.Count & 0xf) << 24;
             word0 |= (ExchangeBuff.Count & 0xf) << 28;
 
-                byte[] handleData = Array.Empty<byte>();
+            using RecyclableMemoryStream handleDataStream = HandleDesc?.GetStream();
-
-                if (HandleDesc != null)
-                {
-                    handleData = HandleDesc.GetBytes();
-                }
 
             int dataLength = RawData?.Length ?? 0;
 
@@ -221,17 +217,20 @@ namespace Ryujinx.HLE.HOS.Ipc
                 word1 |= 1 << 31;
             }
 
-                writer.Write(word0);
+            ms.Write(word0);
-                writer.Write(word1);
+            ms.Write(word1);
-                writer.Write(handleData);
+
+            if (handleDataStream != null)
+            {
+                ms.Write(handleDataStream);
+            }
 
             if (RawData != null)
             {
-                    writer.Write(RawData);
+                ms.Write(RawData);
             }
 
-                return ms.ToArray();
+            return ms;
-            }
         }
 
         private long GetPadSize16(long position)

Ryujinx.HLE/HOS/Ipc/IpcRecvListBuffDesc.cs

@@ -13,13 +13,11 @@ namespace Ryujinx.HLE.HOS.Ipc
             Size = size;
         }
 
-        public IpcRecvListBuffDesc(BinaryReader reader)
+        public IpcRecvListBuffDesc(ulong packedValue)
         {
-            ulong value = reader.ReadUInt64();
+            Position = packedValue & 0xffffffffffff;
 
-            Position = value & 0xffffffffffff;
+            Size = (ushort)(packedValue >> 48);
-
-            Size = (ushort)(value >> 48);
         }
     }
 }

Ryujinx.HLE/HOS/Kernel/Common/KTimeManager.cs

@@ -27,6 +27,9 @@ namespace Ryujinx.HLE.HOS.Kernel.Common
         private bool _keepRunning;
         private long _enforceWakeupFromSpinWait;
 
+        private const long NanosecondsPerSecond = 1000000000L;
+        private const long NanosecondsPerMillisecond = 1000000L;
+
         public KTimeManager(KernelContext context)
         {
             _context = context;
@@ -55,7 +58,7 @@ namespace Ryujinx.HLE.HOS.Kernel.Common
             {
                 _waitingObjects.Add(new WaitingObject(schedulerObj, timePoint));
 
-                if (timeout < 1000000)
+                if (timeout < NanosecondsPerMillisecond)
                 {
                     Interlocked.Exchange(ref _enforceWakeupFromSpinWait, 1);
                 }
@@ -161,7 +164,7 @@ namespace Ryujinx.HLE.HOS.Kernel.Common
 
         public static long ConvertNanosecondsToMilliseconds(long time)
         {
-            time /= 1000000;
+            time /= NanosecondsPerMillisecond;
 
             if ((ulong)time > int.MaxValue)
             {
@@ -173,18 +176,18 @@ namespace Ryujinx.HLE.HOS.Kernel.Common
 
         public static long ConvertMillisecondsToNanoseconds(long time)
         {
-            return time * 1000000;
+            return time * NanosecondsPerMillisecond;
         }
 
         public static long ConvertNanosecondsToHostTicks(long ns)
         {
-            long nsDiv = ns / 1000000000;
+            long nsDiv = ns / NanosecondsPerSecond;
-            long nsMod = ns % 1000000000;
+            long nsMod = ns % NanosecondsPerSecond;
-            long tickDiv = PerformanceCounter.TicksPerSecond / 1000000000;
+            long tickDiv = PerformanceCounter.TicksPerSecond / NanosecondsPerSecond;
-            long tickMod = PerformanceCounter.TicksPerSecond % 1000000000;
+            long tickMod = PerformanceCounter.TicksPerSecond % NanosecondsPerSecond;
 
-            long baseTicks = (nsMod * tickMod + PerformanceCounter.TicksPerSecond - 1) / 1000000000;
+            long baseTicks = (nsMod * tickMod + PerformanceCounter.TicksPerSecond - 1) / NanosecondsPerSecond;
-            return (nsDiv * tickDiv) * 1000000000 + nsDiv * tickMod + nsMod * tickDiv + baseTicks;
+            return (nsDiv * tickDiv) * NanosecondsPerSecond + nsDiv * tickMod + nsMod * tickDiv + baseTicks;
         }
 
         public static long ConvertGuestTicksToNanoseconds(long ticks)

Ryujinx.HLE/HOS/Kernel/SupervisorCall/Syscall.cs

@@ -553,7 +553,7 @@ namespace Ryujinx.HLE.HOS.Kernel.SupervisorCall
 
             KProcess currentProcess = KernelStatic.GetCurrentProcess();
 
-            KSynchronizationObject[] syncObjs = new KSynchronizationObject[handles.Length];
+            KSynchronizationObject[] syncObjs = handles.Length == 0 ? Array.Empty<KSynchronizationObject>() : new KSynchronizationObject[handles.Length];
 
             for (int index = 0; index < handles.Length; index++)
             {

Ryujinx.HLE/HOS/Kernel/Threading/KPriorityQueue.cs

@@ -5,11 +5,11 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
 {
     class KPriorityQueue
     {
-        private LinkedList<KThread>[][] _scheduledThreadsPerPrioPerCore;
+        private readonly LinkedList<KThread>[][] _scheduledThreadsPerPrioPerCore;
-        private LinkedList<KThread>[][] _suggestedThreadsPerPrioPerCore;
+        private readonly LinkedList<KThread>[][] _suggestedThreadsPerPrioPerCore;
 
-        private long[] _scheduledPrioritiesPerCore;
+        private readonly long[] _scheduledPrioritiesPerCore;
-        private long[] _suggestedPrioritiesPerCore;
+        private readonly long[] _suggestedPrioritiesPerCore;
 
         public KPriorityQueue()
         {
@@ -32,43 +32,134 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
             _suggestedPrioritiesPerCore = new long[KScheduler.CpuCoresCount];
         }
 
-        public IEnumerable<KThread> SuggestedThreads(int core)
+        public readonly ref struct KThreadEnumerable
         {
-            return Iterate(_suggestedThreadsPerPrioPerCore, _suggestedPrioritiesPerCore, core);
+            readonly LinkedList<KThread>[][] _listPerPrioPerCore;
+            readonly long[] _prios;
+            readonly int _core;
+
+            public KThreadEnumerable(LinkedList<KThread>[][] listPerPrioPerCore, long[] prios, int core)
+            {
+                _listPerPrioPerCore = listPerPrioPerCore;
+                _prios = prios;
+                _core = core;
             }
 
-        public IEnumerable<KThread> ScheduledThreads(int core)
+            public Enumerator GetEnumerator()
             {
-            return Iterate(_scheduledThreadsPerPrioPerCore, _scheduledPrioritiesPerCore, core);
+                return new Enumerator(_listPerPrioPerCore, _prios, _core);
             }
 
-        private IEnumerable<KThread> Iterate(LinkedList<KThread>[][] listPerPrioPerCore, long[] prios, int core)
+            public ref struct Enumerator
             {
-            long prioMask = prios[core];
+                private readonly LinkedList<KThread>[][] _listPerPrioPerCore;
+                private readonly int _core;
+                private long _prioMask;
+                private int _prio;
+                private LinkedList<KThread> _list;
+                private LinkedListNode<KThread> _node;
 
-            int prio = BitOperations.TrailingZeroCount(prioMask);
+                public Enumerator(LinkedList<KThread>[][] listPerPrioPerCore, long[] prios, int core)
-
-            prioMask &= ~(1L << prio);
-
-            while (prio < KScheduler.PrioritiesCount)
                 {
-                LinkedList<KThread> list = listPerPrioPerCore[prio][core];
+                    _listPerPrioPerCore = listPerPrioPerCore;
-
+                    _core = core;
-                LinkedListNode<KThread> node = list.First;
+                    _prioMask = prios[core];
-
+                    _prio = BitOperations.TrailingZeroCount(_prioMask);
-                while (node != null)
+                    _prioMask &= ~(1L << _prio);
-                {
-                    yield return node.Value;
-
-                    node = node.Next;
                 }
 
-                prio = BitOperations.TrailingZeroCount(prioMask);
+                public KThread Current => _node?.Value;
 
-                prioMask &= ~(1L << prio);
+                public bool MoveNext()
+                {
+                    _node = _node?.Next;
+
+                    if (_node == null)
+                    {
+                        if (!MoveNextListAndFirstNode())
+                        {
+                            return false;
                         }
                     }
 
+                    return _node != null;
+                }
+
+                private bool MoveNextListAndFirstNode()
+                {
+                    if (_prio < KScheduler.PrioritiesCount)
+                    {
+                        _list = _listPerPrioPerCore[_prio][_core];
+
+                        _node = _list.First;
+
+                        _prio = BitOperations.TrailingZeroCount(_prioMask);
+
+                        _prioMask &= ~(1L << _prio);
+
+                        return true;
+                    }
+                    else
+                    {
+                        _list = null;
+                        _node = null;
+                        return false;
+                    }
+                }
+            }
+        }
+
+        public KThreadEnumerable ScheduledThreads(int core)
+        {
+            return new KThreadEnumerable(_scheduledThreadsPerPrioPerCore, _scheduledPrioritiesPerCore, core);
+        }
+
+        public KThreadEnumerable SuggestedThreads(int core)
+        {
+            return new KThreadEnumerable(_suggestedThreadsPerPrioPerCore, _suggestedPrioritiesPerCore, core);
+        }
+
+        public KThread ScheduledThreadsFirstOrDefault(int core)
+        {
+            return ScheduledThreadsElementAtOrDefault(core, 0);
+        }
+
+        public KThread ScheduledThreadsElementAtOrDefault(int core, int index)
+        {
+            int currentIndex = 0;
+            foreach (var scheduledThread in ScheduledThreads(core))
+            {
+                if (currentIndex == index)
+                {
+                    return scheduledThread;
+                }
+                else
+                {
+                    currentIndex++;
+                }
+            }
+
+            return null;
+        }
+
+        public KThread ScheduledThreadsWithDynamicPriorityFirstOrDefault(int core, int dynamicPriority)
+        {
+            foreach (var scheduledThread in ScheduledThreads(core))
+            {
+                if (scheduledThread.DynamicPriority == dynamicPriority)
+                {
+                    return scheduledThread;
+                }
+            }
+
+            return null;
+        }
+
+        public bool HasScheduledThreads(int core)
+        {
+            return ScheduledThreadsFirstOrDefault(core) != null;
+        }
+
         public void TransferToCore(int prio, int dstCore, KThread thread)
         {
             int srcCore = thread.ActiveCore;

Ryujinx.HLE/HOS/Kernel/Threading/KScheduler.cs

@@ -1,8 +1,6 @@
 using Ryujinx.Common;
 using Ryujinx.HLE.HOS.Kernel.Process;
 using System;
-using System.Collections.Generic;
-using System.Linq;
 using System.Numerics;
 using System.Threading;
 
@@ -17,6 +15,8 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
 
         private static readonly int[] PreemptionPriorities = new int[] { 59, 59, 59, 63 };
 
+        private static readonly int[] _srcCoresHighestPrioThreads = new int[CpuCoresCount];
+
         private readonly KernelContext _context;
         private readonly int _coreId;
 
@@ -86,7 +86,7 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
 
             for (int core = 0; core < CpuCoresCount; core++)
             {
-                KThread thread = context.PriorityQueue.ScheduledThreads(core).FirstOrDefault();
+                KThread thread = context.PriorityQueue.ScheduledThreadsFirstOrDefault(core);
 
                 if (thread != null &&
                     thread.Owner != null &&
@@ -115,12 +115,12 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
             {
                 // If the core is not idle (there's already a thread running on it),
                 // then we don't need to attempt load balancing.
-                if (context.PriorityQueue.ScheduledThreads(core).Any())
+                if (context.PriorityQueue.HasScheduledThreads(core))
                 {
                     continue;
                 }
 
-                int[] srcCoresHighestPrioThreads = new int[CpuCoresCount];
+                Array.Fill(_srcCoresHighestPrioThreads, 0);
 
                 int srcCoresHighestPrioThreadsCount = 0;
 
@@ -136,7 +136,7 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
                         break;
                     }
 
-                    srcCoresHighestPrioThreads[srcCoresHighestPrioThreadsCount++] = suggested.ActiveCore;
+                    _srcCoresHighestPrioThreads[srcCoresHighestPrioThreadsCount++] = suggested.ActiveCore;
                 }
 
                 // Not yet selected candidate found.
@@ -158,9 +158,9 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
                 // (the first one that doesn't make the source core idle if moved).
                 for (int index = 0; index < srcCoresHighestPrioThreadsCount; index++)
                 {
-                    int srcCore = srcCoresHighestPrioThreads[index];
+                    int srcCore = _srcCoresHighestPrioThreads[index];
 
-                    KThread src = context.PriorityQueue.ScheduledThreads(srcCore).ElementAtOrDefault(1);
+                    KThread src = context.PriorityQueue.ScheduledThreadsElementAtOrDefault(srcCore, 1);
 
                     if (src != null)
                     {
@@ -422,9 +422,7 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
 
         private static void RotateScheduledQueue(KernelContext context, int core, int prio)
         {
-            IEnumerable<KThread> scheduledThreads = context.PriorityQueue.ScheduledThreads(core);
+            KThread selectedThread = context.PriorityQueue.ScheduledThreadsWithDynamicPriorityFirstOrDefault(core, prio);
-
-            KThread selectedThread = scheduledThreads.FirstOrDefault(x => x.DynamicPriority == prio);
             KThread nextThread = null;
 
             // Yield priority queue.
@@ -433,14 +431,14 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
                 nextThread = context.PriorityQueue.Reschedule(prio, core, selectedThread);
             }
 
-            IEnumerable<KThread> SuitableCandidates()
+            static KThread FirstSuitableCandidateOrDefault(KernelContext context, int core, KThread selectedThread, KThread nextThread, Predicate< KThread> predicate)
             {
                 foreach (KThread suggested in context.PriorityQueue.SuggestedThreads(core))
                 {
                     int suggestedCore = suggested.ActiveCore;
                     if (suggestedCore >= 0)
                     {
-                        KThread selectedSuggestedCore = context.PriorityQueue.ScheduledThreads(suggestedCore).FirstOrDefault();
+                        KThread selectedSuggestedCore = context.PriorityQueue.ScheduledThreadsFirstOrDefault(suggestedCore);
 
                         if (selectedSuggestedCore == suggested || (selectedSuggestedCore != null && selectedSuggestedCore.DynamicPriority < 2))
                         {
@@ -453,14 +451,19 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
                         nextThread == null ||
                         nextThread.LastScheduledTime >= suggested.LastScheduledTime)
                     {
-                        yield return suggested;
+                        if (predicate(suggested))
+                        {
+                            return suggested;
                         }
                     }
                 }
 
+                return null;
+            }
+
             // Select candidate threads that could run on this core.
             // Only take into account threads that are not yet selected.
-            KThread dst = SuitableCandidates().FirstOrDefault(x => x.DynamicPriority == prio);
+            KThread dst = FirstSuitableCandidateOrDefault(context, core, selectedThread, nextThread, x => x.DynamicPriority == prio);
 
             if (dst != null)
             {
@@ -469,11 +472,11 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
 
             // If the priority of the currently selected thread is lower or same as the preemption priority,
             // then try to migrate a thread with lower priority.
-            KThread bestCandidate = context.PriorityQueue.ScheduledThreads(core).FirstOrDefault();
+            KThread bestCandidate = context.PriorityQueue.ScheduledThreadsFirstOrDefault(core);
 
             if (bestCandidate != null && bestCandidate.DynamicPriority >= prio)
             {
-                dst = SuitableCandidates().FirstOrDefault(x => x.DynamicPriority < bestCandidate.DynamicPriority);
+                dst = FirstSuitableCandidateOrDefault(context, core, selectedThread, nextThread, x => x.DynamicPriority < bestCandidate.DynamicPriority);
 
                 if (dst != null)
                 {
@@ -534,7 +537,7 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
             // Move current thread to the end of the queue.
             KThread nextThread = context.PriorityQueue.Reschedule(prio, core, currentThread);
 
-            IEnumerable<KThread> SuitableCandidates()
+            static KThread FirstSuitableCandidateOrDefault(KernelContext context, int core, KThread nextThread, int lessThanOrEqualPriority)
             {
                 foreach (KThread suggested in context.PriorityQueue.SuggestedThreads(core))
                 {
@@ -554,12 +557,17 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
                     if (suggested.LastScheduledTime <= nextThread.LastScheduledTime ||
                         suggested.DynamicPriority < nextThread.DynamicPriority)
                     {
-                        yield return suggested;
+                        if (suggested.DynamicPriority <= lessThanOrEqualPriority)
+                        {
+                            return suggested;
                         }
                     }
                 }
 
-            KThread dst = SuitableCandidates().FirstOrDefault(x => x.DynamicPriority <= prio);
+                return null;
+            }
+
+            KThread dst = FirstSuitableCandidateOrDefault(context, core, nextThread, prio);
 
             if (dst != null)
             {
@@ -596,7 +604,7 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
 
             context.PriorityQueue.TransferToCore(currentThread.DynamicPriority, -1, currentThread);
 
-            if (!context.PriorityQueue.ScheduledThreads(core).Any())
+            if (!context.PriorityQueue.HasScheduledThreads(core))
             {
                 KThread selectedThread = null;
 
@@ -609,7 +617,7 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
                         continue;
                     }
 
-                    KThread firstCandidate = context.PriorityQueue.ScheduledThreads(suggestedCore).FirstOrDefault();
+                    KThread firstCandidate = context.PriorityQueue.ScheduledThreadsFirstOrDefault(suggestedCore);
 
                     if (firstCandidate == suggested)
                     {

Ryujinx.HLE/HOS/Kernel/Threading/KSynchronization.cs

@@ -59,7 +59,7 @@ namespace Ryujinx.HLE.HOS.Kernel.Threading
             }
             else
             {
-                LinkedListNode<KThread>[] syncNodes = new LinkedListNode<KThread>[syncObjs.Length];
+                LinkedListNode<KThread>[] syncNodes = syncObjs.Length == 0 ? Array.Empty<LinkedListNode<KThread>>() : new LinkedListNode<KThread>[syncObjs.Length];
 
                 for (int index = 0; index < syncObjs.Length; index++)
                 {

Ryujinx.HLE/HOS/Services/Am/AppletAE/Storage/StorageHelper.cs

@@ -1,4 +1,5 @@
-using Ryujinx.HLE.HOS.Services.Account.Acc;
+using Ryujinx.Common.Memory;
+using Ryujinx.HLE.HOS.Services.Account.Acc;
 using System.IO;
 
 namespace Ryujinx.HLE.HOS.Services.Am.AppletAE.Storage
@@ -10,7 +11,7 @@ namespace Ryujinx.HLE.HOS.Services.Am.AppletAE.Storage
         public static byte[] MakeLaunchParams(UserProfile userProfile)
         {
             // Size needs to be at least 0x88 bytes otherwise application errors.
-            using (MemoryStream ms = new MemoryStream())
+            using (MemoryStream ms = MemoryStreamManager.Shared.GetStream())
             {
                 BinaryWriter writer = new BinaryWriter(ms);
 

Ryujinx.HLE/HOS/Services/Sdb/Pl/SharedFontManager.cs

@@ -5,6 +5,7 @@ using LibHac.FsSystem;
 using LibHac.Ncm;
 using LibHac.Tools.FsSystem;
 using LibHac.Tools.FsSystem.NcaUtils;
+using Ryujinx.Common.Memory;
 using Ryujinx.HLE.Exceptions;
 using Ryujinx.HLE.FileSystem;
 using Ryujinx.HLE.HOS.Kernel.Memory;
@@ -160,7 +161,7 @@ namespace Ryujinx.HLE.HOS.Services.Sdb.Pl
             static uint KXor(uint data) => data ^ FontKey;
 
             using (BinaryReader reader    = new BinaryReader(bfttfStream))
-            using (MemoryStream ttfStream = new MemoryStream())
+            using (MemoryStream ttfStream = MemoryStreamManager.Shared.GetStream())
             using (BinaryWriter output    = new BinaryWriter(ttfStream))
             {
                 if (KXor(reader.ReadUInt32()) != BFTTFMagic)

Ryujinx.HLE/HOS/Services/ServerBase.cs

@@ -1,3 +1,5 @@
+using Ryujinx.Common;
+using Ryujinx.Common.Memory;
 using Ryujinx.HLE.HOS.Ipc;
 using Ryujinx.HLE.HOS.Kernel;
 using Ryujinx.HLE.HOS.Kernel.Ipc;
@@ -5,6 +7,7 @@ using Ryujinx.HLE.HOS.Kernel.Process;
 using Ryujinx.HLE.HOS.Kernel.Threading;
 using Ryujinx.Horizon.Common;
 using System;
+using System.Buffers;
 using System.Buffers.Binary;
 using System.Collections.Generic;
 using System.IO;
@@ -37,14 +40,27 @@ namespace Ryujinx.HLE.HOS.Services
         private readonly Dictionary<int, IpcService> _sessions = new Dictionary<int, IpcService>();
         private readonly Dictionary<int, Func<IpcService>> _ports = new Dictionary<int, Func<IpcService>>();
 
+        private readonly MemoryStream _requestDataStream;
+        private readonly BinaryReader _requestDataReader;
+
+        private readonly MemoryStream _responseDataStream;
+        private readonly BinaryWriter _responseDataWriter;
+
         public ManualResetEvent InitDone { get; }
         public string Name { get; }
         public Func<IpcService> SmObjectFactory { get; }
 
         public ServerBase(KernelContext context, string name, Func<IpcService> smObjectFactory = null)
         {
-            InitDone = new ManualResetEvent(false);
             _context = context;
+
+            _requestDataStream = MemoryStreamManager.Shared.GetStream();
+            _requestDataReader = new BinaryReader(_requestDataStream);
+
+            _responseDataStream = MemoryStreamManager.Shared.GetStream();
+            _responseDataWriter = new BinaryWriter(_responseDataStream);
+
+            InitDone = new ManualResetEvent(false);
             Name = name;
             SmObjectFactory = smObjectFactory;
 
@@ -110,15 +126,15 @@ namespace Ryujinx.HLE.HOS.Services
 
             while (true)
             {
-                int[] portHandles = _portHandles.ToArray();
+                int handleCount = _portHandles.Count + _sessionHandles.Count;
-                int[] sessionHandles = _sessionHandles.ToArray();
-                int[] handles = new int[portHandles.Length + sessionHandles.Length];
 
-                portHandles.CopyTo(handles, 0);
+                int[] handles = ArrayPool<int>.Shared.Rent(handleCount);
-                sessionHandles.CopyTo(handles, portHandles.Length);
+                
+                _portHandles.CopyTo(handles, 0);
+                _sessionHandles.CopyTo(handles, _portHandles.Count);
 
                 // We still need a timeout here to allow the service to pick up and listen new sessions...
-                var rc = _context.Syscall.ReplyAndReceive(out int signaledIndex, handles, replyTargetHandle, 1000000L);
+                var rc = _context.Syscall.ReplyAndReceive(out int signaledIndex, handles.AsSpan(0, handleCount), replyTargetHandle, 1000000L);
 
                 thread.HandlePostSyscall();
 
@@ -129,7 +145,7 @@ namespace Ryujinx.HLE.HOS.Services
 
                 replyTargetHandle = 0;
 
-                if (rc == Result.Success && signaledIndex >= portHandles.Length)
+                if (rc == Result.Success && signaledIndex >= _portHandles.Count)
                 {
                     // We got a IPC request, process it, pass to the appropriate service if needed.
                     int signaledHandle = handles[signaledIndex];
@@ -156,6 +172,8 @@ namespace Ryujinx.HLE.HOS.Services
                     _selfProcess.CpuMemory.Write(messagePtr + 0x4, 2 << 10);
                     _selfProcess.CpuMemory.Write(messagePtr + 0x8, heapAddr | ((ulong)PointerBufferSize << 48));
                 }
+
+                ArrayPool<int>.Shared.Return(handles);
             }
 
             Dispose();
@@ -166,13 +184,9 @@ namespace Ryujinx.HLE.HOS.Services
             KProcess process = KernelStatic.GetCurrentProcess();
             KThread thread = KernelStatic.GetCurrentThread();
             ulong messagePtr = thread.TlsAddress;
-            ulong messageSize = 0x100;
 
-            byte[] reqData = new byte[messageSize];
+            IpcMessage request = ReadRequest(process, messagePtr);
 
-            process.CpuMemory.Read(messagePtr, reqData);
-
-            IpcMessage request = new IpcMessage(reqData, (long)messagePtr);
             IpcMessage response = new IpcMessage();
 
             ulong tempAddr = recvListAddr;
@@ -202,18 +216,16 @@ namespace Ryujinx.HLE.HOS.Services
             bool shouldReply = true;
             bool isTipcCommunication = false;
 
-            using (MemoryStream raw = new MemoryStream(request.RawData))
+            _requestDataStream.SetLength(0);
-            {
+            _requestDataStream.Write(request.RawData);
-                BinaryReader reqReader = new BinaryReader(raw);
+            _requestDataStream.Position = 0;
 
             if (request.Type == IpcMessageType.HipcRequest ||
                 request.Type == IpcMessageType.HipcRequestWithContext)
             {
                 response.Type = IpcMessageType.HipcResponse;
 
-                    using (MemoryStream resMs = new MemoryStream())
+                _responseDataStream.SetLength(0);
-                    {
-                        BinaryWriter resWriter = new BinaryWriter(resMs);
 
                 ServiceCtx context = new ServiceCtx(
                     _context.Device,
@@ -222,34 +234,33 @@ namespace Ryujinx.HLE.HOS.Services
                     thread,
                     request,
                     response,
-                            reqReader,
+                    _requestDataReader,
-                            resWriter);
+                    _responseDataWriter);
 
                 _sessions[serverSessionHandle].CallHipcMethod(context);
 
-                        response.RawData = resMs.ToArray();
+                response.RawData = _responseDataStream.ToArray();
-                    }
             }
             else if (request.Type == IpcMessageType.HipcControl ||
                         request.Type == IpcMessageType.HipcControlWithContext)
             {
-                    uint magic = (uint)reqReader.ReadUInt64();
+                uint magic = (uint)_requestDataReader.ReadUInt64();
-                    uint cmdId = (uint)reqReader.ReadUInt64();
+                uint cmdId = (uint)_requestDataReader.ReadUInt64();
 
                 switch (cmdId)
                 {
                     case 0:
-                            request = FillResponse(response, 0, _sessions[serverSessionHandle].ConvertToDomain());
+                        FillHipcResponse(response, 0, _sessions[serverSessionHandle].ConvertToDomain());
                         break;
 
                     case 3:
-                            request = FillResponse(response, 0, PointerBufferSize);
+                        FillHipcResponse(response, 0, PointerBufferSize);
                         break;
 
                     // TODO: Whats the difference between IpcDuplicateSession/Ex?
                     case 2:
                     case 4:
-                            int unknown = reqReader.ReadInt32();
+                        int unknown = _requestDataReader.ReadInt32();
 
                         _context.Syscall.CreateSession(out int dupServerSessionHandle, out int dupClientSessionHandle, false, 0);
 
@@ -257,7 +268,7 @@ namespace Ryujinx.HLE.HOS.Services
 
                         response.HandleDesc = IpcHandleDesc.MakeMove(dupClientSessionHandle);
 
-                            request = FillResponse(response, 0);
+                        FillHipcResponse(response, 0);
 
                         break;
 
@@ -269,10 +280,7 @@ namespace Ryujinx.HLE.HOS.Services
                 _context.Syscall.CloseHandle(serverSessionHandle);
                 _sessionHandles.Remove(serverSessionHandle);
                 IpcService service = _sessions[serverSessionHandle];
-                    if (service is IDisposable disposableObj)
+                (service as IDisposable)?.Dispose();
-                    {
-                        disposableObj.Dispose();
-                    }
                 _sessions.Remove(serverSessionHandle);
                 shouldReply = false;
             }
@@ -284,9 +292,7 @@ namespace Ryujinx.HLE.HOS.Services
                 // Response type is always the same as request on TIPC.
                 response.Type = request.Type;
 
-                    using (MemoryStream resMs = new MemoryStream())
+                _responseDataStream.SetLength(0);
-                    {
-                        BinaryWriter resWriter = new BinaryWriter(resMs);
 
                 ServiceCtx context = new ServiceCtx(
                     _context.Device,
@@ -295,15 +301,15 @@ namespace Ryujinx.HLE.HOS.Services
                     thread,
                     request,
                     response,
-                            reqReader,
+                    _requestDataReader,
-                            resWriter);
+                    _responseDataWriter);
 
                 _sessions[serverSessionHandle].CallTipcMethod(context);
 
-                        response.RawData = resMs.ToArray();
+                response.RawData = _responseDataStream.ToArray();
-                    }
 
-                    process.CpuMemory.Write(messagePtr, response.GetBytesTipc());
+                using var responseStream = response.GetStreamTipc();
+                process.CpuMemory.Write(messagePtr, responseStream.GetReadOnlySequence());
             }
             else
             {
@@ -312,48 +318,55 @@ namespace Ryujinx.HLE.HOS.Services
 
             if (!isTipcCommunication)
             {
-                    process.CpuMemory.Write(messagePtr, response.GetBytes((long)messagePtr, recvListAddr | ((ulong)PointerBufferSize << 48)));
+                using var responseStream = response.GetStream((long)messagePtr, recvListAddr | ((ulong)PointerBufferSize << 48));
+                process.CpuMemory.Write(messagePtr, responseStream.GetReadOnlySequence());
             }
 
             return shouldReply;
         }
-        }
 
-        private static IpcMessage FillResponse(IpcMessage response, long result, params int[] values)
+        private static IpcMessage ReadRequest(KProcess process, ulong messagePtr)
         {
-            using (MemoryStream ms = new MemoryStream())
+            const int messageSize = 0x100;
+
+            byte[] reqData = ArrayPool<byte>.Shared.Rent(messageSize);
+
+            Span<byte> reqDataSpan = reqData.AsSpan(0, messageSize);
+            reqDataSpan.Clear();
+
+            process.CpuMemory.Read(messagePtr, reqDataSpan);
+
+            IpcMessage request = new IpcMessage(reqDataSpan, (long)messagePtr);
+
+            ArrayPool<byte>.Shared.Return(reqData);
+
+            return request;
+        }
+
+        private void FillHipcResponse(IpcMessage response, long result)
         {
-                BinaryWriter writer = new BinaryWriter(ms);
+            FillHipcResponse(response, result, ReadOnlySpan<byte>.Empty);
+        }
 
-                foreach (int value in values)
+        private void FillHipcResponse(IpcMessage response, long result, int value)
         {
-                    writer.Write(value);
+            Span<byte> span = stackalloc byte[sizeof(int)];
+            BinaryPrimitives.WriteInt32LittleEndian(span, value);
+            FillHipcResponse(response, result, span);
         }
 
-                return FillResponse(response, result, ms.ToArray());
+        private void FillHipcResponse(IpcMessage response, long result, ReadOnlySpan<byte> data)
-            }
-        }
-
-        private static IpcMessage FillResponse(IpcMessage response, long result, byte[] data = null)
         {
             response.Type = IpcMessageType.HipcResponse;
 
-            using (MemoryStream ms = new MemoryStream())
+            _responseDataStream.SetLength(0);
-            {
-                BinaryWriter writer = new BinaryWriter(ms);
 
-                writer.Write(IpcMagic.Sfco);
+            _responseDataStream.Write(IpcMagic.Sfco);
-                writer.Write(result);
+            _responseDataStream.Write(result);
 
-                if (data != null)
+            _responseDataStream.Write(data);
-                {
-                    writer.Write(data);
-                }
 
-                response.RawData = ms.ToArray();
+            response.RawData = _responseDataStream.ToArray();
-            }
-
-            return response;
         }
 
         protected virtual void Dispose(bool disposing)
@@ -372,6 +385,11 @@ namespace Ryujinx.HLE.HOS.Services
 
                 _sessions.Clear();
 
+                _requestDataReader.Dispose();
+                _requestDataStream.Dispose();
+                _responseDataWriter.Dispose();
+                _responseDataStream.Dispose();
+
                 InitDone.Dispose();
             }
         }

Ryujinx.HLE/Utilities/StringUtils.cs

@@ -1,4 +1,6 @@
 using LibHac.Common;
+using Microsoft.IO;
+using Ryujinx.Common.Memory;
 using Ryujinx.HLE.HOS;
 using System;
 using System.Globalization;
@@ -77,7 +79,7 @@ namespace Ryujinx.HLE.Utilities
             ulong position = context.Request.PtrBuff[index].Position;
             ulong size     = context.Request.PtrBuff[index].Size;
 
-            using (MemoryStream ms = new MemoryStream())
+            using (RecyclableMemoryStream ms = MemoryStreamManager.Shared.GetStream())
             {
                 while (size-- > 0)
                 {
@@ -91,7 +93,7 @@ namespace Ryujinx.HLE.Utilities
                     ms.WriteByte(value);
                 }
 
-                return Encoding.UTF8.GetString(ms.ToArray());
+                return Encoding.UTF8.GetString(ms.GetReadOnlySequence());
             }
         }
 
@@ -110,7 +112,7 @@ namespace Ryujinx.HLE.Utilities
             ulong position = context.Request.SendBuff[index].Position;
             ulong size     = context.Request.SendBuff[index].Size;
 
-            using (MemoryStream ms = new MemoryStream())
+            using (RecyclableMemoryStream ms = MemoryStreamManager.Shared.GetStream())
             {
                 while (size-- > 0)
                 {
@@ -124,7 +126,7 @@ namespace Ryujinx.HLE.Utilities
                     ms.WriteByte(value);
                 }
 
-                return Encoding.UTF8.GetString(ms.ToArray());
+                return Encoding.UTF8.GetString(ms.GetReadOnlySequence());
             }
         }
 

Ryujinx.Input/Motion/CemuHook/Client.cs

@@ -3,6 +3,7 @@ using Ryujinx.Common.Configuration.Hid;
 using Ryujinx.Common.Configuration.Hid.Controller;
 using Ryujinx.Common.Configuration.Hid.Controller.Motion;
 using Ryujinx.Common.Logging;
+using Ryujinx.Common.Memory;
 using Ryujinx.Input.HLE;
 using Ryujinx.Input.Motion.CemuHook.Protocol;
 using System;
@@ -381,7 +382,7 @@ namespace Ryujinx.Input.Motion.CemuHook
 
             Header header = GenerateHeader(clientId);
 
-            using (MemoryStream stream = new MemoryStream())
+            using (MemoryStream stream = MemoryStreamManager.Shared.GetStream())
             using (BinaryWriter writer = new BinaryWriter(stream))
             {
                 writer.WriteStruct(header);
@@ -421,7 +422,7 @@ namespace Ryujinx.Input.Motion.CemuHook
 
             Header header = GenerateHeader(clientId);
 
-            using (MemoryStream stream = new MemoryStream())
+            using (MemoryStream stream = MemoryStreamManager.Shared.GetStream())
             using (BinaryWriter writer = new BinaryWriter(stream))
             {
                 writer.WriteStruct(header);

Ryujinx.Memory/IVirtualMemoryManager.cs

@@ -1,5 +1,6 @@
 using Ryujinx.Memory.Range;
 using System;
+using System.Buffers;
 using System.Collections.Generic;
 
 namespace Ryujinx.Memory
@@ -77,6 +78,21 @@ namespace Ryujinx.Memory
         /// <exception cref="InvalidMemoryRegionException">Throw for unhandled invalid or unmapped memory accesses</exception>
         void Write(ulong va, ReadOnlySpan<byte> data);
 
+        /// <summary>
+        /// Writes data to CPU mapped memory, with write tracking.
+        /// </summary>
+        /// <param name="va">Virtual address to write the data into</param>
+        /// <param name="data">Data to be written</param>
+        /// <exception cref="InvalidMemoryRegionException">Throw for unhandled invalid or unmapped memory accesses</exception>
+        public void Write(ulong va, ReadOnlySequence<byte> data)
+        {
+            foreach (ReadOnlyMemory<byte> segment in data)
+            {
+                Write(va, segment.Span);
+                va += (ulong)segment.Length;
+            }
+        }
+
         /// <summary>
         /// Writes data to the application process, returning false if the data was not changed.
         /// This triggers read memory tracking, as a redundancy check would be useless if the data is not up to date.

Ryujinx/Ui/Windows/AvatarWindow.cs

@@ -6,6 +6,7 @@ using LibHac.FsSystem;
 using LibHac.Ncm;
 using LibHac.Tools.FsSystem;
 using LibHac.Tools.FsSystem.NcaUtils;
+using Ryujinx.Common.Memory;
 using Ryujinx.HLE.FileSystem;
 using Ryujinx.Ui.Common.Configuration;
 using SixLabors.ImageSharp;
@@ -136,8 +137,8 @@ namespace Ryujinx.Ui.Windows
 
                             romfs.OpenFile(ref file.Ref, ("/" + item.FullPath).ToU8Span(), OpenMode.Read).ThrowIfFailure();
 
-                            using (MemoryStream stream    = new MemoryStream())
+                            using (MemoryStream stream    = MemoryStreamManager.Shared.GetStream())
-                            using (MemoryStream streamPng = new MemoryStream())
+                            using (MemoryStream streamPng = MemoryStreamManager.Shared.GetStream())
                             {
                                 file.Get.AsStream().CopyTo(stream);
 
@@ -169,7 +170,7 @@ namespace Ryujinx.Ui.Windows
 
         private byte[] ProcessImage(byte[] data)
         {
-            using (MemoryStream streamJpg = new MemoryStream())
+            using (MemoryStream streamJpg = MemoryStreamManager.Shared.GetStream())
             {
                 Image avatarImage = Image.Load(data, new PngDecoder());
 

Ryujinx/Ui/Windows/UserProfilesManagerWindow.cs

@@ -1,4 +1,5 @@
 using Gtk;
+using Ryujinx.Common.Memory;
 using Ryujinx.HLE.FileSystem;
 using Ryujinx.HLE.HOS.Services.Account.Acc;
 using Ryujinx.Ui.Common.Configuration;
@@ -181,7 +182,7 @@ namespace Ryujinx.Ui.Windows
             {
                 image.Mutate(x => x.Resize(256, 256));
 
-                using (MemoryStream streamJpg = new MemoryStream())
+                using (MemoryStream streamJpg = MemoryStreamManager.Shared.GetStream())
                 {
                     image.SaveAsJpeg(streamJpg);