audio: set thread priority with audio_thread_priority

shukusai/src/audio/audio.rs

@@ -169,12 +169,12 @@ impl Audio {
 		let mut tries = 0_usize;
 		let output = loop {
 			 match AudioOutput::dummy() {
-				Ok(o) => { debug!("Audio Init [1/2] ... dummy output device"); break o; },
+				Ok(o) => { debug!("Audio Init [1/3] ... dummy output device"); break o; },
 				Err(e) => {
 					if tries == 5 {
-						warn!("Audio Init [1/2] ... output device error: {e:?} ... will continue to retry every {RETRY_SECONDS} seconds, but will only log when we succeed");
+						warn!("Audio Init [1/3] ... output device error: {e:?} ... will continue to retry every {RETRY_SECONDS} seconds, but will only log when we succeed");
 					} else if tries < 5 {
-						warn!("Audio Init [1/2] ... output device error: {e:?} ... retrying in {RETRY_SECONDS} seconds");
+						warn!("Audio Init [1/3] ... output device error: {e:?} ... retrying in {RETRY_SECONDS} seconds");
 					}
 					tries += 1;
 				},
@@ -187,16 +187,16 @@ impl Audio {
 		let media_controls = if media_controls {
 			match crate::audio::media_controls::init_media_controls(to_audio) {
 				Ok(mc) => {
-					debug!("Audio Init [2/2] ... media controls");
+					debug!("Audio Init [2/3] ... media controls");
 					Some(mc)
 				},
 				Err(e) => {
-					warn!("Audio Init [2/2] ... media controls failed: {e}");
+					warn!("Audio Init [2/3] ... media controls failed: {e}");
 					None
 				},
 			}
 		} else {
-			debug!("Audio Init [2/2] ... skipping media controls");
+			debug!("Audio Init [2/3] ... skipping media controls");
 			None
 		};
 
@@ -219,6 +219,15 @@ impl Audio {
 			from_kernel,
 		};
 
+		// Set real-time thread priority.
+		match audio_thread_priority::promote_current_thread_to_real_time(
+			0,      // audio buffer frames (0 == default sensible value)
+			96_000, // audio sample rate (assume 96Hz)
+		) {
+			Ok(_)  => ok_debug!("Audio Init [3/3] ... realtime priority"),
+			Err(_) => fail!("Audio Init [3/3] ... realtime priority"),
+		}
+
 		// Start `main()`.
 		Self::main(audio);
 	}

shukusai/src/kernel/kernel.rs

@@ -448,13 +448,6 @@ impl Kernel {
 		match std::thread::Builder::new()
 			.name("Audio".to_string())
 			.spawn(move || {
-				#[cfg(unix)]
-				{
-					// SAFETY: libc is used to set niceness.
-					let nice = unsafe { libc::nice(-20) };
-					debug!("Audio ... spawned at niceness level: {nice}");
-				}
-
 				Audio::init(collection, audio, audio_send, audio_recv, media_controls);
 		}) {
 			Ok(_)  => debug!("Kernel Init [11/13] ... spawned Audio"),