Android Boot Optimization using BootChart

 Hi Guys!!!

Hope you are doing well !. After long time I am back. Sorry for late to add new blogs. 

Today I am sharing details on Boot optimization using BootChart .  

First What is boot process. I have written one blog in 2017 with complete details on bootprocess. 

Android Boot Process 

Here is summary :-

The boot process is a chain of actions starting from the boot ROM, followed by the Bootloader, Kernel, Init, Zygote, and System Server (bold indicates Android-specific boot process).

 In the automotive-specific boot process, early services such as rearview camera must start during the Kernel boot.

Now coming to the point. Below are the few avilable point to do optimization .

• Bootloader
• Device kernel
• I/O tuning
• init.*.rc
• Boot animation
• SELinux policy

Tool and methods

Today I am discussing BootChart. 

Bootchart provides CPU and I/O load breakdown of all processes for the whole system.

To enable bootchart:

1. In Current User-debug Build 

To enable bootchart in current flashed user-debug build

adb shell 'touch /data/bootchart/enabled'
adb reboot

After boot up, fetch boot chart:

$ANDROID_BUILD_TOP/system/core/init/grab-bootchart.sh

When finished, delete /data/bootchart/enabled to prevent collecting the data every time.

2. Enable at compile time

$ Android_Build_Top_Dir/system/core/init 

In bootchar.h modification BootChart :

#ifndef BOOTCHART
# define BOOTCHART 1
#endif

$ touch init.c
$ mm INIT_BOOTCHART=true

Triggering bootchart functionality on system boot

adb shell 'echo 120 > /data/bootchart-start' 

Retrieving the collected data from the system

system/core/init/grab-bootchart.sh

Analyzing the results

Use any image viewer to examine the graphic.Things to look for

•  Start and top times of the various processes, and 
• Their CPU utilization. 

Long gaps with low utilization may indicate a timeout or some other problem.

Once you have identified the processes that are using time during the initialization, you can further analyze these by looking at system logs, using strace, and examining the system source code.

Mostly usual suspects

1. In Kernel Init

• ip_auto_config
• USB init
• Flash driver initialization 

The standard Kernel optimizing

2. In Zygote

Preloading Android Framework has thousands of Java classes Preloaded by Zygote and instantiated in its heap To improve Application startup time and save memory Controlled by resource

 frameworks/base/preloaded-classes

Zygote Class Preloading Can use the tool in framework to adjust the list: 

$ adb logcat > logcat.txt 

$ java -p preload.jar Compile logcat.txt logcat.compiled 

$ java -p preload.jar PrintCsv logcat.compiled 

3. In PackageManager

Package Scannig Every APK is scanned at boot time Package management code is inefficient Uses mmaped files means each access will cause page fault ParseZipArchive() scans entire APK for only one AndroidManifest.xml file

4. In System Services

Starting Last stage of Android boot Start every base service Zygote start SystemServer process Start native service (SurfaceFlinger, AudioFlinger) first Start each service sequentially

Thanks

Saurabh

Happy Coding!!!!