Merge pull request #1673 from NZJenkins/perf_tweaks

Add sleeps/waits in various places

src/core/hle/DSOUND/DirectSound/DirectSound.cpp

@@ -525,9 +525,10 @@ static void dsound_thread_worker(LPVOID nullPtr)
 {
 	SetThreadAffinityMask(GetCurrentThread(), g_CPUOthers);
 
-    while (true) {
-		Sleep(0);
-        DSoundMutexGuardLock;
+    while (true) {
+		Sleep(1);
+
+        DSoundMutexGuardLock;
 
         vector_ds_stream::iterator ppDSStream = g_pDSoundStreamCache.begin();
         for (; ppDSStream != g_pDSoundStreamCache.end(); ppDSStream++) {

src/core/kernel/init/CxbxKrnl.cpp

@@ -657,6 +657,7 @@ void TriggerPendingConnectedInterrupts()
 		if (HalSystemInterrupts[i].IsPending() && EmuInterruptList[i] && EmuInterruptList[i]->Connected) {
 			HalSystemInterrupts[i].Trigger(EmuInterruptList[i]);
 		}
+		SwitchToThread();
 	}
 }
 

src/core/kernel/support/EmuFS.cpp

@@ -125,15 +125,23 @@ uint32_t fs_lock = 0;
 __declspec(naked) void LockFS()
 {
 	__asm {
-		pushfd
-		pushad
-		spinlock :
-		mov eax, 1
-		xchg eax, fs_lock
-		test eax, eax
-		jnz spinlock
-		popad
-		popfd
+		// Backup Registers
+		pushfd
+		pushad
+
+		// Spin until we can aquire the lock
+		spinlock :
+		call SwitchToThread // Give other threads chance to run, prevents hogging entire timeslice waiting for spinlock
+							// We do this here loop because SwitchToThread will overwrite eax, so it cannot go below
+							// It's not worth wasting the extra cycles of pushing/popping eax to the stack around this call
+		mov eax, 1
+		xchg eax, fs_lock
+		test eax, eax
+		jnz spinlock
+
+		// Restore registers and return
+		popad
+		popfd
 		ret
 	}
 }