Compact system processes.

Compact system processes soon after boot and during idle maintenance. This
will help keep the pagecache in a more consistent state.

Test: boots, works
bug 119988524

Change-Id: I7207d6ba3a2047278b767718dbc532e06f5516fd

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

@@ -5121,6 +5121,7 @@ public class ActivityManagerService extends IActivityManager.Stub
                                 String data, Bundle extras, boolean ordered,
                                 boolean sticky, int sendingUser) {
                             synchronized (ActivityManagerService.this) {
+                                mOomAdjuster.mAppCompact.compactAllSystem();
                                 requestPssAllProcsLocked(SystemClock.uptimeMillis(), true, false);
                             }
                         }
@@ -8614,6 +8615,10 @@ public class ActivityManagerService extends IActivityManager.Stub
         synchronized (this) {
             final long now = SystemClock.uptimeMillis();
             final long timeSinceLastIdle = now - mLastIdleTime;
+
+            // Compact all non-zygote processes to freshen up the page cache.
+            mOomAdjuster.mAppCompact.compactAllSystem();
+
             final long lowRamSinceLastIdle = getLowRamTimeSinceIdle(now);
             mLastIdleTime = now;
             mLowRamTimeSinceLastIdle = 0;

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

@@ -92,6 +92,7 @@ public final class AppCompactor {
     static final int COMPACT_PROCESS_PERSISTENT = 3;
     static final int COMPACT_PROCESS_BFGS = 4;
     static final int COMPACT_PROCESS_MSG = 1;
+    static final int COMPACT_SYSTEM_MSG = 2;
 
     /**
      * This thread must be moved to the system background cpuset.
@@ -264,6 +265,16 @@ public final class AppCompactor {
                 || (now - app.lastCompactTime) > mCompactThrottleBFGS);
     }
 
+    @GuardedBy("mAm")
+    void compactAllSystem() {
+        if (mUseCompaction) {
+            mCompactionHandler.sendMessage(mCompactionHandler.obtainMessage(
+                                              COMPACT_SYSTEM_MSG));
+        }
+    }
+
+    private native void compactSystem();
+
     /**
      * Reads the flag value from DeviceConfig to determine whether app compaction
      * should be enabled, and starts/stops the compaction thread as needed.
@@ -497,6 +508,13 @@ public final class AppCompactor {
                         // nothing to do, presumably the process died
                         Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
                     }
+                    break;
+                }
+                case COMPACT_SYSTEM_MSG: {
+                    Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "compactSystem");
+                    compactSystem();
+                    Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
+                    break;
                 }
             }
         }

services/core/jni/Android.bp

@@ -50,6 +50,7 @@ cc_library_static {
         "com_android_server_VibratorService.cpp",
         "com_android_server_PersistentDataBlockService.cpp",
         "com_android_server_GraphicsStatsService.cpp",
+        "com_android_server_am_AppCompactor.cpp",
         "onload.cpp",
     ],
 

services/core/jni/com_android_server_am_AppCompactor.cpp

@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "AppCompactor"
+//#define LOG_NDEBUG 0
+
+#include <dirent.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <android-base/stringprintf.h>
+#include <android-base/file.h>
+
+#include <nativehelper/JNIHelp.h>
+#include <android_runtime/AndroidRuntime.h>
+#include <jni.h>
+
+using android::base::StringPrintf;
+using android::base::WriteStringToFile;
+
+namespace android {
+
+// This performs per-process reclaim on all processes belonging to non-app UIDs.
+// For the most part, these are non-zygote processes like Treble HALs, but it
+// also includes zygote-derived processes that run in system UIDs, like bluetooth
+// or potentially some mainline modules. The only process that should definitely
+// not be compacted is system_server, since compacting system_server around the
+// time of BOOT_COMPLETE could result in perceptible issues.
+static void com_android_server_am_AppCompactor_compactSystem(JNIEnv *, jobject) {
+    std::unique_ptr<DIR, decltype(&closedir)> proc(opendir("/proc"), closedir);
+    struct dirent* current;
+    while ((current = readdir(proc.get()))) {
+        if (current->d_type != DT_DIR) {
+            continue;
+        }
+
+        // don't compact system_server, rely on persistent compaction during screen off
+        // in order to avoid mmap_sem-related stalls
+        if (atoi(current->d_name) == getpid()) {
+            continue;
+        }
+
+        std::string status_name = StringPrintf("/proc/%s/status", current->d_name);
+        struct stat status_info;
+
+        if (stat(status_name.c_str(), &status_info) != 0) {
+            // must be some other directory that isn't a pid
+            continue;
+        }
+
+        // android.os.Process.FIRST_APPLICATION_UID
+        if (status_info.st_uid >= 10000) {
+            continue;
+        }
+
+        std::string reclaim_path = StringPrintf("/proc/%s/reclaim", current->d_name);
+        WriteStringToFile(std::string("all"), reclaim_path);
+    }
+}
+
+static const JNINativeMethod sMethods[] = {
+    /* name, signature, funcPtr */
+    {"compactSystem", "()V", (void*)com_android_server_am_AppCompactor_compactSystem},
+};
+
+int register_android_server_am_AppCompactor(JNIEnv* env)
+{
+    return jniRegisterNativeMethods(env, "com/android/server/am/AppCompactor",
+                                    sMethods, NELEM(sMethods));
+}
+
+}

services/core/jni/onload.cpp

@@ -54,6 +54,7 @@ int register_android_server_GraphicsStatsService(JNIEnv* env);
 int register_android_hardware_display_DisplayViewport(JNIEnv* env);
 int register_android_server_net_NetworkStatsService(JNIEnv* env);
 int register_android_server_security_VerityUtils(JNIEnv* env);
+int register_android_server_am_AppCompactor(JNIEnv* env);
 };
 
 using namespace android;
@@ -101,5 +102,6 @@ extern "C" jint JNI_OnLoad(JavaVM* vm, void* /* reserved */)
     register_android_hardware_display_DisplayViewport(env);
     register_android_server_net_NetworkStatsService(env);
     register_android_server_security_VerityUtils(env);
+    register_android_server_am_AppCompactor(env);
     return JNI_VERSION_1_4;
 }