OutputThread: use real-time priority

NEWS

@@ -18,6 +18,7 @@ ver 0.19 (not yet released)
   - shine: new encoder plugin
 * new resampler option using libsoxr
 * the update thread runs at "idle" priority
+* the output thread runs at "real-time" priority
 
 ver 0.18.7 (2013/01/13)
 * playlist

src/OutputThread.cxx

@@ -30,6 +30,7 @@
 #include "PlayerControl.hxx"
 #include "MusicPipe.hxx"
 #include "MusicChunk.hxx"
+#include "thread/Util.hxx"
 #include "system/FatalError.hxx"
 #include "util/Error.hxx"
 #include "Log.hxx"
@@ -578,6 +579,8 @@ audio_output_task(void *arg)
 {
 	struct audio_output *ao = (struct audio_output *)arg;
 
+	SetThreadRealtime();
+
 	ao->mutex.lock();
 
 	while (1) {

src/thread/Util.hxx

@@ -69,4 +69,17 @@ SetThreadIdlePriority()
 #endif
 };
 
+/**
+ * Raise the current thread's priority to "real-time" (very high).
+ */
+static inline void
+SetThreadRealtime()
+{
+#ifdef __linux__
+	struct sched_param sched_param;
+	sched_param.sched_priority = 50;
+	sched_setscheduler(0, SCHED_FIFO, &sched_param);
+#endif
+};
+
 #endif