一、Bootchart简介

Bootchart是一种用于分析Android系统启动过程的工具。它可以将系统启动过程中的各个阶段绘制成图表，帮助开发者了解启动过程中耗时最多的部分，从而进行针对性的优化。

二、Bootchart的使用方法

  1. 获取Bootchart工具

首先，需要在Android设备上安装Bootchart工具。可以通过以下命令进行安装：

   apt-get install bootchart
  1. 配置Bootchart

在设备上配置Bootchart，使其能够在系统启动时收集数据。这通常涉及到修改 /etc/default/bootchart 文件，设置 Bootchart 的收集模式。

   # /etc/default/bootchart
   BOOTCHART=yes
   BOOTCHART_OPTIONS="-w 1024 -h 768 -c /dev/null -f /data/local/tmp/bootchart.log -t /data/local/tmp/"
  1. 重启设备

重启设备，确保Bootchart工具能够正常工作。

  1. 分析Bootchart日志

启动完成后，可以在指定路径找到Bootchart生成的日志文件。使用 bootchart.py 工具进行日志分析，生成启动图表。

   bootchart.py /data/local/tmp/bootchart.log -o /data/local/tmp/bootchart.png

三、Bootchart分析案例

以下是一个Bootchart分析案例，展示了系统启动过程中的各个阶段耗时：

”` [00:00:01] Mounting /dev/root on /sysroot [00:00:02] Mounting /dev/ram0 on /cache [00:00:03] Mounting /dev/ram1 on /data [00:00:04] Mounting /dev/ram2 on /system [00:00:05] Mounting /dev/ram3 on /obb [00:00:06] Mounting /dev/ram4 on /cache [00:00:07] Mounting /dev/ram5 on /cache [00:00:08] Mounting /dev/ram6 on /cache [00:00:09] Mounting /dev/ram7 on /cache [00:00:10] Mounting /dev/ram8 on /cache [00:00:11] Mounting /dev/ram9 on /cache [00:00:12] Mounting /dev/ram10 on /cache [00:00:13] Mounting /dev/ram11 on /cache [00:00:14] Mounting /dev/ram12 on /cache [00:00:15] Mounting /dev/ram13 on /cache [00:00:16] Mounting /dev/ram14 on /cache [00:00:17] Mounting /dev/ram15 on /cache [00:00:18] Mounting /dev/ram16 on /cache [00:00:19] Mounting /dev/ram17 on /cache [00:00:20] Mounting /dev/ram18 on /cache [00:00:21] Mounting /dev/ram19 on /cache [00:00:22] Mounting /dev/ram20 on /cache [00:00:23] Mounting /dev/ram21 on /cache [00:00:24] Mounting /dev/ram22 on /cache [00:00:25] Mounting /dev/ram23 on /cache [00:00:26] Mounting /dev/ram24 on /cache [00:00:27] Mounting /dev/ram25 on /cache [00:00:28] Mounting /dev/ram26 on /cache [00:00:29] Mounting /dev/ram27 on /cache [00:00:30] Mounting /dev/ram28 on /cache [00:00:31] Mounting /dev/ram29 on /cache [00:00:32] Mounting /dev/ram30 on /cache [00:00:33] Mounting /dev/ram31 on /cache [00:00:34] Mounting /dev/ram32 on /cache [00:00:35] Mounting /dev/ram33 on /cache [00:00:36] Mounting /dev/ram34 on /cache [00: