From 32e5d5910758903df0f7a0b09f1caf8efe12d6f3 Mon Sep 17 00:00:00 2001
From: jhorv <38920027+jhorv@users.noreply.github.com>
Date: Sat, 13 Apr 2024 12:52:15 -0400
Subject: [PATCH] perf: use GetReadOnlySequence() instead of GetSpan()

---
 .../HOS/Kernel/Ipc/KServerSession.cs           |  4 ++--
 .../HOS/Kernel/Memory/KPageTableBase.cs        | 18 +++++++++++-------
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/src/Ryujinx.HLE/HOS/Kernel/Ipc/KServerSession.cs b/src/Ryujinx.HLE/HOS/Kernel/Ipc/KServerSession.cs
index 7e41a3f3aa..3b42808557 100644
--- a/src/Ryujinx.HLE/HOS/Kernel/Ipc/KServerSession.cs
+++ b/src/Ryujinx.HLE/HOS/Kernel/Ipc/KServerSession.cs
@@ -570,7 +570,7 @@ namespace Ryujinx.HLE.HOS.Kernel.Ipc
                 }
                 else
                 {
-                    serverProcess.CpuMemory.Write(copyDst, clientProcess.CpuMemory.GetSpan(copySrc, (int)copySize));
+                    serverProcess.CpuMemory.Write(copyDst, clientProcess.CpuMemory.GetReadOnlySequence(copySrc, (int)copySize));
                 }
 
                 if (clientResult != Result.Success)
@@ -858,7 +858,7 @@ namespace Ryujinx.HLE.HOS.Kernel.Ipc
                 }
                 else
                 {
-                    clientProcess.CpuMemory.Write(copyDst, serverProcess.CpuMemory.GetSpan(copySrc, (int)copySize));
+                    clientProcess.CpuMemory.Write(copyDst, serverProcess.CpuMemory.GetReadOnlySequence(copySrc, (int)copySize));
                 }
             }
 
diff --git a/src/Ryujinx.HLE/HOS/Kernel/Memory/KPageTableBase.cs b/src/Ryujinx.HLE/HOS/Kernel/Memory/KPageTableBase.cs
index c836b06500..bba0a20f18 100644
--- a/src/Ryujinx.HLE/HOS/Kernel/Memory/KPageTableBase.cs
+++ b/src/Ryujinx.HLE/HOS/Kernel/Memory/KPageTableBase.cs
@@ -1569,7 +1569,11 @@ namespace Ryujinx.HLE.HOS.Kernel.Memory
 
                     while (size > 0)
                     {
-                        ulong copySize = 0x100000; // Copy chunck size. Any value will do, moderate sizes are recommended.
+                        // Copy chunk size. Previous impl created copies to write using GetSpan(), and moderate sizes
+                        // were recommended to avoid allocating very large temporary buffers. Since moving to use
+                        // ReadOnlySequence<byte> and reading directly, we set the copySize to the max size of a
+                        // segment: Int32.MaxValue.
+                        ulong copySize = int.MaxValue;
 
                         if (copySize > size)
                         {
@@ -1578,11 +1582,11 @@ namespace Ryujinx.HLE.HOS.Kernel.Memory
 
                         if (toServer)
                         {
-                            currentProcess.CpuMemory.Write(serverAddress, GetSpan(clientAddress, (int)copySize));
+                            currentProcess.CpuMemory.Write(serverAddress, GetReadOnlySequence(clientAddress, (int)copySize));
                         }
                         else
                         {
-                            Write(clientAddress, currentProcess.CpuMemory.GetSpan(serverAddress, (int)copySize));
+                            Write(clientAddress, currentProcess.CpuMemory.GetReadOnlySequence(serverAddress, (int)copySize));
                         }
 
                         serverAddress += copySize;
@@ -1912,9 +1916,9 @@ namespace Ryujinx.HLE.HOS.Kernel.Memory
                     Context.Memory.Fill(GetDramAddressFromPa(dstFirstPagePa), unusedSizeBefore, (byte)_ipcFillValue);
 
                     ulong copySize = addressRounded <= endAddr ? addressRounded - address : size;
-                    var data = srcPageTable.GetSpan(addressTruncated + unusedSizeBefore, (int)copySize);
+                    var data = srcPageTable.GetReadOnlySequence(addressTruncated + unusedSizeBefore, (int)copySize);
 
-                    Context.Memory.Write(GetDramAddressFromPa(dstFirstPagePa + unusedSizeBefore), data);
+                    ((IWritableBlock)Context.Memory).Write(GetDramAddressFromPa(dstFirstPagePa + unusedSizeBefore), data);
 
                     firstPageFillAddress += unusedSizeBefore + copySize;
 
@@ -1978,9 +1982,9 @@ namespace Ryujinx.HLE.HOS.Kernel.Memory
                 if (send)
                 {
                     ulong copySize = endAddr - endAddrTruncated;
-                    var data = srcPageTable.GetSpan(endAddrTruncated, (int)copySize);
+                    var data = srcPageTable.GetReadOnlySequence(endAddrTruncated, (int)copySize);
 
-                    Context.Memory.Write(GetDramAddressFromPa(dstLastPagePa), data);
+                    ((IWritableBlock)Context.Memory).Write(GetDramAddressFromPa(dstLastPagePa), data);
 
                     lastPageFillAddr += copySize;