From 880721b38b861d44af25b3384efffd69bbe47d0c Mon Sep 17 00:00:00 2001
From: Alan Leung <acleung@google.com>
Date: Mon, 16 May 2016 21:12:33 -0700
Subject: [PATCH] Enable boost-locked-region-priority

Enable jack.transformations.boost-locked-region-priority compiler pass
that had shown to increase performance in AmSlam by 10% or so.

bug: 28610549
Change-Id: If1b76787acd272882647ede7e831cb1ba376e578
---
 services/core/Android.mk                      |  6 +++++
 .../server/am/ActivityManagerService.java     | 24 +++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/services/core/Android.mk b/services/core/Android.mk
index 860f60a019365..b965ce39e7d59 100644
--- a/services/core/Android.mk
+++ b/services/core/Android.mk
@@ -24,4 +24,10 @@ ifneq ($(INCREMENTAL_BUILDS),)
     LOCAL_JACK_ENABLED := incremental
 endif
 
+LOCAL_JACK_FLAGS := \
+ -D jack.transformations.boost-locked-region-priority=true \
+ -D jack.transformations.boost-locked-region-priority.classname=com.android.server.am.ActivityManagerService \
+ -D jack.transformations.boost-locked-region-priority.request=com.android.server.am.ActivityManagerService\#boostPriorityForLockedSection \
+ -D jack.transformations.boost-locked-region-priority.reset=com.android.server.am.ActivityManagerService\#resetPriorityAfterLockedSection
+
 include $(BUILD_STATIC_JAVA_LIBRARY)
diff --git a/services/core/java/com/android/server/am/ActivityManagerService.java b/services/core/java/com/android/server/am/ActivityManagerService.java
index dec5e4184bff2..3194d891a0e0b 100644
--- a/services/core/java/com/android/server/am/ActivityManagerService.java
+++ b/services/core/java/com/android/server/am/ActivityManagerService.java
@@ -628,6 +628,30 @@ public final class ActivityManagerService extends ActivityManagerNative
         return mShowDialogs && !mSleeping && !mShuttingDown;
     }
 
+    // it's a semaphore; boost when 0->1, reset when 1->0
+    static ThreadLocal<Integer> sIsBoosted = new ThreadLocal<Integer>() {
+        @Override protected Integer initialValue() {
+            return 0;
+        }
+    };
+
+    static void boostPriorityForLockedSection() {
+        if (sIsBoosted.get() == 0) {
+            // boost to prio 118 while holding a global lock
+            Process.setThreadPriority(Process.myTid(), -2);
+            //Log.e(TAG, "PRIORITY BOOST:  set priority on TID " + Process.myTid());
+        }
+        int cur = sIsBoosted.get();
+        sIsBoosted.set(cur + 1);
+    }
+
+    static void resetPriorityAfterLockedSection() {
+        sIsBoosted.set(sIsBoosted.get() - 1);
+        if (sIsBoosted.get() == 0) {
+            //Log.e(TAG, "PRIORITY BOOST:  reset priority on TID " + Process.myTid());
+            Process.setThreadPriority(Process.myTid(), 0);
+        }
+    }
     public class PendingAssistExtras extends Binder implements Runnable {
         public final ActivityRecord activity;
         public final Bundle extras;