Merge "PlaybackThread: Request real-time priority on ARC" into main
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index 3fdd5cb..767c502 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -223,6 +223,8 @@
 static const int kPriorityAudioApp = 2;
 static const int kPriorityFastMixer = 3;
 static const int kPriorityFastCapture = 3;
+// Request real-time priority for PlaybackThread in ARC
+static const int kPriorityPlaybackThreadArc = 1;
 
 // IAudioFlinger::createTrack() has an in/out parameter 'pFrameCount' for the total size of the
 // track buffer in shared memory.  Zero on input means to use a default value.  For fast tracks,
@@ -3954,6 +3956,27 @@
                 stream()->setHalThreadPriority(priorityBoost);
             }
         }
+    } else if (property_get_bool("ro.boot.container", false /* default_value */)) {
+        // In ARC experiments (b/73091832), the latency under using CFS scheduler with any priority
+        // is not enough for PlaybackThread to process audio data in time. We request the lowest
+        // real-time priority, SCHED_FIFO=1, for PlaybackThread in ARC. ro.boot.container is true
+        // only on ARC.
+        const pid_t tid = getTid();
+        if (tid == -1) {
+            ALOGW("%s: Cannot update PlaybackThread priority for ARC, no tid", __func__);
+        } else {
+            const status_t status = requestPriority(getpid(),
+                                                    tid,
+                                                    kPriorityPlaybackThreadArc,
+                                                    false /* isForApp */,
+                                                    true /* asynchronous */);
+            if (status != OK) {
+                ALOGW("%s: Cannot update PlaybackThread priority for ARC, status %d", __func__,
+                        status);
+            } else {
+                stream()->setHalThreadPriority(kPriorityPlaybackThreadArc);
+            }
+        }
     }
 
     Vector<sp<IAfTrack>> tracksToRemove;