/*
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* Copyright (C) 2019 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.server;
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import android.app.job.JobInfo;
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import android.app.job.JobParameters;
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import android.app.job.JobScheduler;
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import android.app.job.JobService;
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import android.content.ComponentName;
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import android.content.Context;
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import android.os.FileUtils;
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import android.os.SystemProperties;
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import android.util.Slog;
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import java.io.File;
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import java.io.IOException;
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import java.util.concurrent.TimeUnit;
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/**
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* Schedules jobs for triggering zram writeback.
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*/
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public final class ZramWriteback extends JobService {
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private static final String TAG = "ZramWriteback";
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private static final boolean DEBUG = false;
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private static final ComponentName sZramWriteback =
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new ComponentName("android", ZramWriteback.class.getName());
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private static final int MARK_IDLE_JOB_ID = 811;
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private static final int WRITEBACK_IDLE_JOB_ID = 812;
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private static final int MAX_ZRAM_DEVICES = 256;
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private static int sZramDeviceId = 0;
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private static final String IDLE_SYS = "/sys/block/zram%d/idle";
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private static final String IDLE_SYS_ALL_PAGES = "all";
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private static final String WB_SYS = "/sys/block/zram%d/writeback";
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private static final String WB_SYS_IDLE_PAGES = "idle";
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private static final String WB_STATS_SYS = "/sys/block/zram%d/bd_stat";
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private static final int WB_STATS_MAX_FILE_SIZE = 128;
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private static final String BDEV_SYS = "/sys/block/zram%d/backing_dev";
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private static final String MARK_IDLE_DELAY_PROP = "ro.zram.mark_idle_delay_mins";
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private static final String FIRST_WB_DELAY_PROP = "ro.zram.first_wb_delay_mins";
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private static final String PERIODIC_WB_DELAY_PROP = "ro.zram.periodic_wb_delay_hours";
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private void markPagesAsIdle() {
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String idlePath = String.format(IDLE_SYS, sZramDeviceId);
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try {
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FileUtils.stringToFile(new File(idlePath), IDLE_SYS_ALL_PAGES);
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} catch (IOException e) {
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Slog.e(TAG, "Failed to write to " + idlePath);
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}
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}
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private void flushIdlePages() {
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if (DEBUG) Slog.d(TAG, "Start writing back idle pages to disk");
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String wbPath = String.format(WB_SYS, sZramDeviceId);
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try {
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FileUtils.stringToFile(new File(wbPath), WB_SYS_IDLE_PAGES);
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} catch (IOException e) {
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Slog.e(TAG, "Failed to write to " + wbPath);
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}
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if (DEBUG) Slog.d(TAG, "Finished writeback back idle pages");
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}
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private int getWrittenPageCount() {
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String wbStatsPath = String.format(WB_STATS_SYS, sZramDeviceId);
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try {
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String wbStats = FileUtils
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.readTextFile(new File(wbStatsPath), WB_STATS_MAX_FILE_SIZE, "");
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return Integer.parseInt(wbStats.trim().split("\\s+")[2], 10);
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} catch (IOException e) {
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Slog.e(TAG, "Failed to read writeback stats from " + wbStatsPath);
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}
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return -1;
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}
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private void markAndFlushPages() {
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int pageCount = getWrittenPageCount();
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flushIdlePages();
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markPagesAsIdle();
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if (pageCount != -1) {
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Slog.i(TAG, "Total pages written to disk is " + (getWrittenPageCount() - pageCount));
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}
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}
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private static boolean isWritebackEnabled() {
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try {
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String backingDev = FileUtils
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.readTextFile(new File(String.format(BDEV_SYS, sZramDeviceId)), 128, "");
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if (!"none".equals(backingDev.trim())) {
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return true;
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} else {
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Slog.w(TAG, "Writeback device is not set");
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}
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} catch (IOException e) {
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Slog.w(TAG, "Writeback is not enabled on zram");
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}
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return false;
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}
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private static void schedNextWriteback(Context context) {
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int nextWbDelay = SystemProperties.getInt(PERIODIC_WB_DELAY_PROP, 24);
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JobScheduler js = (JobScheduler) context.getSystemService(Context.JOB_SCHEDULER_SERVICE);
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js.schedule(new JobInfo.Builder(WRITEBACK_IDLE_JOB_ID, sZramWriteback)
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.setMinimumLatency(TimeUnit.HOURS.toMillis(nextWbDelay))
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.setRequiresDeviceIdle(true)
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.build());
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}
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@Override
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public boolean onStartJob(JobParameters params) {
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if (!isWritebackEnabled()) {
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jobFinished(params, false);
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return false;
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}
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if (params.getJobId() == MARK_IDLE_JOB_ID) {
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markPagesAsIdle();
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jobFinished(params, false);
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return false;
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} else {
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new Thread("ZramWriteback_WritebackIdlePages") {
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@Override
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public void run() {
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markAndFlushPages();
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schedNextWriteback(ZramWriteback.this);
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jobFinished(params, false);
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}
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}.start();
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}
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return true;
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}
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@Override
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public boolean onStopJob(JobParameters params) {
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// The thread that triggers the writeback is non-interruptible
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return false;
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}
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/**
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* Schedule the zram writeback job to trigger a writeback when idle
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*/
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public static void scheduleZramWriteback(Context context) {
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int markIdleDelay = SystemProperties.getInt(MARK_IDLE_DELAY_PROP, 20);
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int firstWbDelay = SystemProperties.getInt(FIRST_WB_DELAY_PROP, 180);
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JobScheduler js = (JobScheduler) context.getSystemService(Context.JOB_SCHEDULER_SERVICE);
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// Schedule a one time job to mark pages as idle. These pages will be written
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// back at later point if they remain untouched.
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js.schedule(new JobInfo.Builder(MARK_IDLE_JOB_ID, sZramWriteback)
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.setMinimumLatency(TimeUnit.MINUTES.toMillis(markIdleDelay))
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.setOverrideDeadline(TimeUnit.MINUTES.toMillis(markIdleDelay))
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.build());
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// Schedule a one time job to flush idle pages to disk.
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// After the initial writeback, subsequent writebacks are done at interval set
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// by ro.zram.periodic_wb_delay_hours.
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js.schedule(new JobInfo.Builder(WRITEBACK_IDLE_JOB_ID, sZramWriteback)
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.setMinimumLatency(TimeUnit.MINUTES.toMillis(firstWbDelay))
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.setRequiresDeviceIdle(true)
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.build());
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}
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}
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