RESTRICT AUTOMERGE: Disable file compaction by default

At present time kernel does not support shared pages to be
swapped using file compaction which uses MADV_COLD and most
of the file pages in a process are actually shared mappings
causing us to waste a lot of cycles scanning through a lot
of unreclaimable pages, this patch disables file compaction
which will be reenabled until a solution is implemented on
upstream kernel that allows reclaiming shared pages, thus
making it worth to scan all of those pages again.

Test: am compact file <processname> <uid>
Bug: 265473345
Change-Id: I4c819058da229c00d1eafea636f89784718adc5f
(cherry picked from commit 30b069612a)

services/core/java/com/android/server/am/CachedAppOptimizer.java

@@ -110,6 +110,8 @@ public final class CachedAppOptimizer {
 
     private static final String ATRACE_COMPACTION_TRACK = "Compaction";
 
+    @VisibleForTesting static final boolean ENABLE_FILE_COMPACT = false;
+
     // Defaults for phenotype flags.
     @VisibleForTesting static final Boolean DEFAULT_USE_COMPACTION = false;
     @VisibleForTesting static final Boolean DEFAULT_USE_FREEZER = true;
@@ -515,9 +517,11 @@ public final class CachedAppOptimizer {
 
     @GuardedBy("mProcLock")
     void compactAppSome(ProcessRecord app, boolean force) {
-        app.mOptRecord.setReqCompactAction(COMPACT_PROCESS_SOME);
-        ++mSomeCompactRequest;
-        compactApp(app, force, "some");
+        if (ENABLE_FILE_COMPACT) {
+            app.mOptRecord.setReqCompactAction(COMPACT_PROCESS_SOME);
+            ++mSomeCompactRequest;
+            compactApp(app, force, "some");
+        }
     }
 
     // This method returns true only if requirements are met. Note, that requirements are different
@@ -1278,6 +1282,15 @@ public final class CachedAppOptimizer {
             }
         }
 
+        if (!ENABLE_FILE_COMPACT) {
+            // Turn off file compaction
+            if (resolvedAction == COMPACT_ACTION_FULL) {
+                resolvedAction = COMPACT_ACTION_ANON;
+            } else if (resolvedAction == COMPACT_ACTION_FILE) {
+                resolvedAction = COMPACT_ACTION_NONE;
+            }
+        }
+
         return resolvedAction;
     }
 
@@ -1545,6 +1558,9 @@ public final class CachedAppOptimizer {
                     }
 
                     int resolvedAction = resolveCompactionAction(requestedAction);
+                    if (resolvedAction == COMPACT_ACTION_NONE) {
+                        return;
+                    }
                     action = compactActionIntToString(resolvedAction);
 
                     try {

services/tests/mockingservicestests/src/com/android/server/am/CachedAppOptimizerTest.java

@@ -1079,14 +1079,16 @@ public final class CachedAppOptimizerTest {
 
         mCachedAppOptimizerUnderTest.mLastCompactionStats.clear();
 
-        // We force a some compaction
-        mCachedAppOptimizerUnderTest.compactAppSome(processRecord, true);
-        waitForHandler();
-        // then process is compacted.
-        String executedCompactAction =
+        if (CachedAppOptimizer.ENABLE_FILE_COMPACT) {
+            // We force a some compaction
+            mCachedAppOptimizerUnderTest.compactAppSome(processRecord, true);
+            waitForHandler();
+            // then process is compacted.
+            String executedCompactAction =
                 compactActionIntToString(processRecord.mOptRecord.getLastCompactAction());
-        assertThat(executedCompactAction)
+            assertThat(executedCompactAction)
                 .isEqualTo(mCachedAppOptimizerUnderTest.mCompactActionSome);
+        }
     }
 
     private void setFlag(String key, String value, boolean defaultValue) throws Exception {