snes-add gui option for ring buffer mode. its unclear whether it speeds things up, but its possible that it might, and it was a lot of work, so here it is as a user option.

BizHawk.Emulation/Consoles/Nintendo/SNES/LibsnesApi.cs

@@ -1,9 +1,4 @@
-//controls whether the new shared memory ring buffer communication system is used
-//on the whole it seems to boost performance slightly for me, at the cost of exacerbating spikes
-//not sure if we should keep it
-#define USE_BUFIO
-
-using System;
+using System;
 using System.Linq;
 using System.Diagnostics;
 using System.Globalization;
@@ -550,22 +545,19 @@ namespace BizHawk.Emulation.Consoles.Nintendo.SNES
 
 		public void BeginBufferIO()
 		{
-#if USE_BUFIO
 			bufio = true;
 			WritePipeMessage(eMessage.eMessage_BeginBufferIO);
 			rstream.SetCurrStream(rbufstr);
 			wstream.SetCurrStream(wbufstr);
-#endif
 		}
 
 		public void EndBufferIO()
 		{
-#if USE_BUFIO
+			if(!bufio) return;
 			bufio = false;
 			WritePipeMessage(eMessage.eMessage_EndBufferIO);
 			rstream.SetCurrStream(pipe);
 			wstream.SetCurrStream(pipe);
-#endif
 		}
 
 		void WritePipeString(string str)

BizHawk.Emulation/Consoles/Nintendo/SNES/LibsnesCore.cs

@@ -344,7 +344,8 @@ namespace BizHawk.Emulation.Consoles.Nintendo.SNES
 		{
 			api.MessageCounter = 0;
 
-			api.BeginBufferIO();
+			if(CoreComm.SNES_UseRingBuffer)
+				api.BeginBufferIO();
 
 			// for deterministic emulation, save the state we're going to use before frame advance
 			// don't do this during nocallbacks though, since it's already been done

BizHawk.Emulation/Interfaces/CoreComms.cs

@@ -17,6 +17,7 @@ namespace BizHawk
 
 		public string SNES_ExePath;
 		public string SNES_Profile;
+		public bool SNES_UseRingBuffer;
 
 		public bool SNES_ShowBG1_0, SNES_ShowBG2_0, SNES_ShowBG3_0, SNES_ShowBG4_0;
 		public bool SNES_ShowBG1_1, SNES_ShowBG2_1, SNES_ShowBG3_1, SNES_ShowBG4_1;

BizHawk.MultiClient/BizHawk.MultiClient.csproj

@@ -1018,12 +1018,6 @@
     <None Include="images\reboot.png" />
     <None Include="images\SNESControllerIcon.png" />
     <None Include="images\pencil.png" />
-    <Content Include="output\gamedb_sega_md.txt" />
-    <Content Include="output\gamedb.txt" />
-    <Content Include="output\gamedb_neshomebrew.txt" />
-    <Content Include="output\gamedb_pce_cd.txt" />
-    <Content Include="output\gamedb_pce_hucards.txt" />
-    <Content Include="output\gamedb_sega_8bit.txt" />
     <None Include="images\Refresh.bmp" />
     <None Include="images\TruncateFromRW.png" />
     <None Include="images\TruncateFromFile.png" />

BizHawk.MultiClient/Config.cs

@@ -749,6 +749,7 @@ namespace BizHawk.MultiClient
 		public SNESControllerTemplate[] SNESAutoController = new SNESControllerTemplate[4];
 		public NESConsoleButtonTemplate SNESConsoleButtons = new NESConsoleButtonTemplate();
 		public string SNESProfile = "Compatibility";
+		public bool SNESUseRingBuffer = true;
 
 		//TI 83 settings
 		public TI83ControllerTemplate[] TI83Controller = new TI83ControllerTemplate[1];

BizHawk.MultiClient/MainForm.MenuItems.cs

@@ -1814,12 +1814,15 @@ namespace BizHawk.MultiClient
 		private void miSnesOptions_Click(object sender, EventArgs e)
 		{
 			var so = new SNESOptions();
+			so.UseRingBuffer = Global.Config.SNESUseRingBuffer;
 			so.Profile = Global.Config.SNESProfile;
 			if (so.ShowDialog() == System.Windows.Forms.DialogResult.OK)
 			{
 				bool reboot = Global.Config.SNESProfile != so.Profile;
 				Global.Config.SNESProfile = so.Profile;
+				Global.Config.SNESUseRingBuffer = so.UseRingBuffer;
 				if (reboot) FlagNeedsReboot();
+				SyncCoreCommInputSignals();
 			}
 		}
 

BizHawk.MultiClient/MainForm.cs

@@ -431,6 +431,7 @@ namespace BizHawk.MultiClient
 			target.SNES_ShowOBJ_3 = Global.Config.SNES_ShowOBJ4;
 
 			target.SNES_Profile = Global.Config.SNESProfile;
+			target.SNES_UseRingBuffer = Global.Config.SNESUseRingBuffer;
 
 			target.GG_HighlightActiveDisplayRegion = Global.Config.GGHighlightActiveDisplayRegion;
 			target.GG_ShowClippedRegions = Global.Config.GGShowClippedRegions;

BizHawk.MultiClient/SNESTools/SNESOptions.Designer.cs

@@ -33,13 +33,15 @@
 			this.rbCompatibility = new System.Windows.Forms.RadioButton();
 			this.groupBox1 = new System.Windows.Forms.GroupBox();
 			this.rbPerformance = new System.Windows.Forms.RadioButton();
+			this.cbRingbuf = new System.Windows.Forms.CheckBox();
+			this.label1 = new System.Windows.Forms.Label();
 			this.groupBox1.SuspendLayout();
 			this.SuspendLayout();
 			// 
 			// btnOk
 			// 
 			this.btnOk.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Right)));
-			this.btnOk.Location = new System.Drawing.Point(141, 102);
+			this.btnOk.Location = new System.Drawing.Point(141, 172);
 			this.btnOk.Name = "btnOk";
 			this.btnOk.Size = new System.Drawing.Size(75, 23);
 			this.btnOk.TabIndex = 0;
@@ -51,7 +53,7 @@
 			// 
 			this.btnCancel.Anchor = ((System.Windows.Forms.AnchorStyles)((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Right)));
 			this.btnCancel.DialogResult = System.Windows.Forms.DialogResult.Cancel;
-			this.btnCancel.Location = new System.Drawing.Point(222, 102);
+			this.btnCancel.Location = new System.Drawing.Point(222, 172);
 			this.btnCancel.Name = "btnCancel";
 			this.btnCancel.Size = new System.Drawing.Size(75, 23);
 			this.btnCancel.TabIndex = 1;
@@ -91,6 +93,25 @@
 			this.rbPerformance.TabStop = true;
 			this.rbPerformance.Text = "Performance (only for casual gaming!)";
 			this.rbPerformance.UseVisualStyleBackColor = true;
+			// 
+			// cbRingbuf
+			// 
+			this.cbRingbuf.AutoSize = true;
+			this.cbRingbuf.Location = new System.Drawing.Point(18, 97);
+			this.cbRingbuf.Name = "cbRingbuf";
+			this.cbRingbuf.Size = new System.Drawing.Size(115, 17);
+			this.cbRingbuf.TabIndex = 4;
+			this.cbRingbuf.Text = "Use Ring Buffer IO";
+			this.cbRingbuf.UseVisualStyleBackColor = true;
+			// 
+			// label1
+			// 
+			this.label1.Location = new System.Drawing.Point(34, 117);
+			this.label1.Name = "label1";
+			this.label1.Size = new System.Drawing.Size(254, 45);
+			this.label1.TabIndex = 5;
+			this.label1.Text = "This was designed as an optimization but it isn\'t clear whether it works. Feel fr" +
+    "ee to try different settings and let us know the results.";
 			// 
 			// SNESOptions
 			// 
@@ -98,7 +119,9 @@
 			this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
 			this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
 			this.CancelButton = this.btnCancel;
-			this.ClientSize = new System.Drawing.Size(300, 128);
+			this.ClientSize = new System.Drawing.Size(300, 198);
+			this.Controls.Add(this.label1);
+			this.Controls.Add(this.cbRingbuf);
 			this.Controls.Add(this.groupBox1);
 			this.Controls.Add(this.btnCancel);
 			this.Controls.Add(this.btnOk);
@@ -107,6 +130,7 @@
 			this.groupBox1.ResumeLayout(false);
 			this.groupBox1.PerformLayout();
 			this.ResumeLayout(false);
+			this.PerformLayout();
 
 		}
 
@@ -117,5 +141,7 @@
 		private System.Windows.Forms.RadioButton rbCompatibility;
 		private System.Windows.Forms.GroupBox groupBox1;
 		private System.Windows.Forms.RadioButton rbPerformance;
+		private System.Windows.Forms.CheckBox cbRingbuf;
+		private System.Windows.Forms.Label label1;
 	}
 }

BizHawk.MultiClient/SNESTools/SNESOptions.cs

@@ -26,6 +26,12 @@ namespace BizHawk.MultiClient
 			}
 		}
 
+		public bool UseRingBuffer
+		{
+			get { return cbRingbuf.Checked; }
+			set { cbRingbuf.Checked = value; }
+		}
+
 		private void btnOk_Click(object sender, EventArgs e)
 		{
 			DialogResult = System.Windows.Forms.DialogResult.OK;