【Android12】Android性能调优工具SystemServerTiming日志

Android性能调优工具SystemServerTiming日志

性能优化、稳定性优化是Android系统优化的两大方面，对于性能调试Android提供了很多工具，比如：bootchart、systrace、perfboot、log、dmsg等等。

SystemServerTiming 是Android原生系统中一个日志标签，也就是tag为SystemServerTiming的日志，这类日志信息会输出到Logd和Trace系统中。可以通过Android logcat 或者抓取Systrace的方式取得。

SystemServerTiming主要用于记录SystemServer中启动各种服务的耗时信息。在性能优化分析的场景下，利用该Log我们分析出SystemServer中各个服务在启动性能上是否存异常，特别是在SystemServer中自定义追加的Service。

SystemServerTiming日志的一段例子

bash 复制代码

# 示意log日志
11-20 23:58:20.766 21530 21530 I SystemServerTiming: InitBeforeStartServices
.................. 21530 21530 I SystemServerTiming: StartServices
.................. 21530 21530 I SystemServerTiming: startBootstrapServices
.................. 21530 21530 I SystemServerTiming: StartWatchdog
.................. 21530 21530 I SystemServerTiming: ReadingSystemConfig
.................. 21530 21530 I SystemServerTiming: PlatformCompat
.................. 21530 21530 I SystemServerTiming: StartFileIntegrityService
.................. 21530 21530 I SystemServerTiming: StartInstaller
.................. 21530 21530 I SystemServerTiming: DeviceIdentifiersPolicyService
.................. 21530 21530 I SystemServerTiming: UriGrantsManagerService
.................. 21530 21530 I SystemServerTiming: StartPowerStatsService
.................. 21530 21530 I SystemServerTiming: StartIStatsService
.................. 21530 21530 I SystemServerTiming: MemtrackProxyService
# 非User编译模式下，会输出统计每个阶段耗时的Log
.................. 21530 21530 I SystemServerTiming: InitBeforeStartServices took to complete: ***ms
...
.................. 21530 21530 I SystemServerTiming: startCoreServices
...
.................. 21530 21530 I SystemServerTiming: startOtherServices
.................. 21530 21530 I SystemServerTiming: SecondaryZygotePreload
...
.................. 21530 21530 I SystemServerTiming: StartSystemUI

SystemServerTiming日志的源码实现
TimingsTraceAndSlog.java 源文件中，定义了SystemServerTiming日志标签，并通过Slog(输出到Logd的System分区)和Trace实现日志的输出。
源码路径：/frameworks/base/services/core/java/com/android/server/utils/TimingsTraceAndSlog.java

java 复制代码

/*
 * 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.
 */
package com.android.server.utils;

import android.annotation.NonNull;
import android.os.Trace;
import android.util.Slog;
import android.util.TimingsTraceLog;

/**
 * Helper class for reporting boot and shutdown timing metrics, also logging to {@link Slog}.
 */
public final class TimingsTraceAndSlog extends TimingsTraceLog {

    /**
    * Tag for timing measurement of main thread.
    */
    public static final String SYSTEM_SERVER_TIMING_TAG = "SystemServerTiming";

    /**
     * Tag for timing measurement of non-main asynchronous operations.
     */
    private static final String SYSTEM_SERVER_TIMING_ASYNC_TAG = SYSTEM_SERVER_TIMING_TAG + "Async";

    /**
     * Set this to a positive value to get a {@Slog.w} log for any trace that took longer than it.
     */
    private static final long BOTTLENECK_DURATION_MS = -1;

    private final String mTag;

    /**
     * Creates a new {@link TimingsTraceAndSlog} for async operations.
     */
    @NonNull
    public static TimingsTraceAndSlog newAsyncLog() {
        return new TimingsTraceAndSlog(SYSTEM_SERVER_TIMING_ASYNC_TAG,
                Trace.TRACE_TAG_SYSTEM_SERVER);
    }

    /**
     * Default constructor using {@code system_server} tags.
     */
    public TimingsTraceAndSlog() {
        this(SYSTEM_SERVER_TIMING_TAG);
    }

    /**
     * Custom constructor using {@code system_server} trace tag.
     *
     * @param tag {@code logcat} tag
     */
    public TimingsTraceAndSlog(@NonNull String tag) {
        this(tag, Trace.TRACE_TAG_SYSTEM_SERVER);
    }

    /**
     * Custom constructor.
     *
     * @param tag {@code logcat} tag
     * @param traceTag {@code atrace} tag
     */
    public TimingsTraceAndSlog(@NonNull String tag, long traceTag) {
        super(tag, traceTag);
        mTag = tag;
    }

    @Override
    public void traceBegin(@NonNull String name) {
        // 使用Slog的Info级别输出
        Slog.i(mTag, name);
        // 调用父类TimingsTraceLog接口，输出Trace
        super.traceBegin(name);
    }

    @Override
    public void logDuration(String name, long timeMs) {
        super.logDuration(name, timeMs);
        if (BOTTLENECK_DURATION_MS > 0 && timeMs >= BOTTLENECK_DURATION_MS) {
            Slog.w(mTag, "Slow duration for " + name + ": " + timeMs + "ms");
        }
    }

    @Override
    public String toString() {
        return "TimingsTraceAndSlog[" + mTag + "]";
    }
}

父类TimingsTraceLog 中的相关实现。

java 复制代码

/*
 * Copyright (C) 2016 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.
 */

package android.util;

import android.annotation.NonNull;
import android.os.Build;
import android.os.SystemClock;
import android.os.Trace;

import com.android.internal.annotations.VisibleForTesting;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * Helper class for reporting boot and shutdown timing metrics.
 *
 * <p><b>NOTE:</b> This class is not thread-safe. Use a separate copy for other threads.
 *
 * @hide
 */
public class TimingsTraceLog {
    // Debug boot time for every step if it's non-user build.
    // 注意：只有在非user编译下，才会输出每个阶段的耗时信息（耗时信息，也可以通过查看log日志的时间戳）
    private static final boolean DEBUG_BOOT_TIME = !Build.IS_USER;

    // Maximum number of nested calls that are stored
    private static final int MAX_NESTED_CALLS = 10;

    private final String[] mStartNames;
    private final long[] mStartTimes;

    private final String mTag;
    private final long mTraceTag;
    private final long mThreadId;
    private final int mMaxNestedCalls;

    private int mCurrentLevel = -1;

    public TimingsTraceLog(String tag, long traceTag) {
        this(tag, traceTag, DEBUG_BOOT_TIME ? MAX_NESTED_CALLS : -1);
    }

    @VisibleForTesting
    public TimingsTraceLog(String tag, long traceTag, int maxNestedCalls) {
        mTag = tag;
        mTraceTag = traceTag;
        mThreadId = Thread.currentThread().getId();
        mMaxNestedCalls = maxNestedCalls;
        if (maxNestedCalls > 0) {
            mStartNames = new String[maxNestedCalls];
            mStartTimes = new long[maxNestedCalls];
        } else {
            mStartNames = null;
            mStartTimes = null;
        }
    }

    /**
     * Begin tracing named section
     * @param name name to appear in trace
     */
    public void traceBegin(String name) {
        assertSameThread();
        Trace.traceBegin(mTraceTag, name);

        if (!DEBUG_BOOT_TIME) return;

        if (mCurrentLevel + 1 >= mMaxNestedCalls) {
            Slog.w(mTag, "not tracing duration of '" + name + "' because already reached "
                    + mMaxNestedCalls + " levels");
            return;
        }

        mCurrentLevel++;
        mStartNames[mCurrentLevel] = name;
        mStartTimes[mCurrentLevel] = SystemClock.elapsedRealtime();
    }

    /**
     * End tracing previously {@link #traceBegin(String) started} section.
     *
     * <p>Also {@link #logDuration logs} the duration.
     */
    public void traceEnd() {
        assertSameThread();
        Trace.traceEnd(mTraceTag);

        if (!DEBUG_BOOT_TIME) return;

        if (mCurrentLevel < 0) {
            Slog.w(mTag, "traceEnd called more times than traceBegin");
            return;
        }

        final String name = mStartNames[mCurrentLevel];
        final long duration = SystemClock.elapsedRealtime() - mStartTimes[mCurrentLevel];
        mCurrentLevel--;

        logDuration(name, duration);
    }

    private void assertSameThread() {
        final Thread currentThread = Thread.currentThread();
        if (currentThread.getId() != mThreadId) {
            throw new IllegalStateException("Instance of TimingsTraceLog can only be called from "
                    + "the thread it was created on (tid: " + mThreadId + "), but was from "
                    + currentThread.getName() + " (tid: " + currentThread.getId() + ")");
        }
    }

    /**
     * Logs a duration so it can be parsed by external tools for performance reporting.
     */
    public void logDuration(String name, long timeMs) {
        Slog.d(mTag, name + " took to complete: " + timeMs + "ms");
    }

    /**
     * Gets the names of the traces that {@link #traceBegin(String) have begun} but
     * {@link #traceEnd() have not finished} yet.
     *
     * <p><b>NOTE:</b> this method is expensive and it should not be used in "production" - it
     * should only be used for debugging purposes during development (and/or guarded by
     * static {@code DEBUG} constants that are {@code false}).
     */
    @NonNull
    public final List<String> getUnfinishedTracesForDebug() {
        if (mStartTimes == null || mCurrentLevel < 0) return Collections.emptyList();
        final ArrayList<String> list = new ArrayList<>(mCurrentLevel + 1);
        for (int i = 0; i <= mCurrentLevel; i++) {
            list.add(mStartNames[i]);
        }
        return list;
    }
}

SystemServer中输出SystemServerTiming日志。SystemServer会在其run函数中创建TimingsTraceAndSlog对象，然后调用这个对象的traceBegin和traceEnd函数。

java 复制代码

// frameworks/base/services/java/com/android/server/SystemServer.java
  private void run() {
       TimingsTraceAndSlog t = new TimingsTraceAndSlog();
       try {
       	   // 使用SystemServerTiming日志标签输出
           t.traceBegin("InitBeforeStartServices");
        // 省略....
     
        // Start services.
        try {
            t.traceBegin("StartServices");
            startBootstrapServices(t);
            startCoreServices(t);
            startOtherServices(t);
        } catch (Throwable ex) {
            Slog.e("System", "******************************************");
            Slog.e("System", "************ Failure starting system services", ex);
            throw ex;
        } finally {
            t.traceEnd(); // StartServices
        }
       // 省略... 
}