Improve Transition GC initiation by improving the Frameworks triggering

signal

Transition GC should be initiated when the app status transitions into
the cached state from a non-cached state.

Test: Local testing
Bug: 272381448
Change-Id: I483a3ddaa11ed037d32c5481999fd996e2e2629a

1 files changed, 15 insertions, 6 deletions

diff --git a/core/java/android/app/ActivityThread.java b/core/java/android/app/ActivityThread.java
index e709a1ac2d36..30a2303a5e41 100644
--- a/core/java/android/app/ActivityThread.java
+++ b/core/java/android/app/ActivityThread.java
@@ -3434,8 +3434,13 @@ public final class ActivityThread extends ClientTransactionHandler
             if (mLastProcessState == processState) {
                 return;
             }
+            // Do not issue a transitional GC if we are transitioning between 2 cached states.
+            // Only update if the state flips between cached and uncached or vice versa
+            if (ActivityManager.isProcStateCached(mLastProcessState)
+                    != ActivityManager.isProcStateCached(processState)) {
+                updateVmProcessState(processState);
+            }
             mLastProcessState = processState;
-            updateVmProcessState(processState);
             if (localLOGV) {
                 Slog.i(TAG, "******************* PROCESS STATE CHANGED TO: " + processState
                         + (fromIpc ? " (from ipc" : ""));
@@ -3444,12 +3449,16 @@ public final class ActivityThread extends ClientTransactionHandler
     }
 
     /** Update VM state based on ActivityManager.PROCESS_STATE_* constants. */
+    // Currently ART VM only uses state updates for Transitional GC, and thus
+    // this function initiates a Transitional GC for transitions into Cached apps states.
     private void updateVmProcessState(int processState) {
-        // TODO: Tune this since things like gmail sync are important background but not jank
-        // perceptible.
-        final int state = processState <= ActivityManager.PROCESS_STATE_IMPORTANT_FOREGROUND
-                ? VM_PROCESS_STATE_JANK_PERCEPTIBLE
-                : VM_PROCESS_STATE_JANK_IMPERCEPTIBLE;
+        // Only a transition into Cached state should result in a Transitional GC request
+        // to the ART runtime. Update VM state to JANK_IMPERCEPTIBLE in that case.
+        // Note that there are 4 possible cached states currently, all of which are
+        // JANK_IMPERCEPTIBLE from GC point of view.
+        final int state = ActivityManager.isProcStateCached(processState)
+                ? VM_PROCESS_STATE_JANK_IMPERCEPTIBLE
+                : VM_PROCESS_STATE_JANK_PERCEPTIBLE;
         VMRuntime.getRuntime().updateProcessState(state);
     }