Bootcharting

Introduction

Optimizing boot time for Android devices is essential for improving overall android performance and enhancing user experience. A quicker boot allows users to start using their devices faster and generally indicates a more efficient system. However, the Android boot process is complex, involving steps like linux boot kernel initialization, system service startup, and app loading, each potentially causing delays. To analyze and optimize this boot sequence, developers rely on robust tools that provide detailed visualizations of system activity and identify bottlenecks. Among these tools, bootcharting in Android plays a vital role by helping visualize and diagnose boot performance issues.

Understanding Bootcharting in Android

Bootcharting in Android refers to the process of capturing detailed metrics during device startup to analyze performance. Bootchart originally was originally used as a Linux tool and was later adapted for Android systems. This tool records key boot metrics such as CPU usage, disk input/output, process start and end times, and idle intervals. After collecting data during boot, bootcharting in Android generates a visual timeline that clearly shows these metrics, enabling developers to pinpoint processes or operations that cause slowdowns.
The resulting chart visualizes each process’s runtime window alongside CPU load and disk activity, making it easier to identify resource-heavy or blocking operations impacting boot speed.

Setting Up Bootcharting in Android Devices

To enable android bootcharting, support must be activated either at compile-time or runtime:

• Compile-Time Activation:
  By setting INIT_BOOTCHART=true during the Android system build, bootcharting begins tracing from the earliest boot stages. This is often configured within the android init build settings.
• Runtime Activation:
  On user-debug or rooted devices, bootcharting can be enabled by creating the file /data/bootchart/enabled via ADB:

  adb shell 'touch /data/bootchart/enabled'
  

  This enables bootcharting on the next boot. Additional kernel flags like CONFIG_BOOTCHART=y (enabling sys kernel tracing) or running a bootchartd daemon may be necessary for full support.
  For in-depth setup, consult the official Android bootchart instructions which provide detailed guidance for enabling and using bootcharting in Android.

Bootcharting in Android: Data Collection Process

Once bootcharting in Android is enabled, you control how long data is collected during startup:

• Using /data/bootchart-start:
  Writing a duration in seconds into /data/bootchart-start sets the logging period. For example, to collect 120 seconds of data:

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

• Emulator Bootcharting:
  Start an Android emulator with bootcharting enabled by passing:

  emulator -bootchart 120
  

  which records data for 120 seconds automatically.

• Kernel Command-Line Parameters:
  Some devices accept bootcharting options directly from the kernel boot parameters.
  Logging stops either automatically after the set time, upon the sys.boot_completed system property being set, or manually by:

adb shell 'echo 1 > /data/bootchart-stop'

Retrieving and Processing Bootcharting Data in Android

After a boot with bootcharting enabled, logs are saved under /data/bootchart/, including:

• header with system info
• proc_stat.log (CPU usage)
• proc_ps.log (process details)
• proc_diskstats.log (disk statistics)
• kernel_pacct (accounting data)
  To extract these logs from an Android device, you can use the grab-bootchart.sh script from the android-bootchart GitHub repository, or manually archive and pull:

adb shell 'cd /data/bootchart && tar -zcf bootchart.tgz *'
adb pull /data/bootchart/bootchart.tgz .

On your development machine, install the bootchart utility (part of bootchart2 packages) to convert this data into a graphical PNG:

bootchart bootchart.tgz

Bootcharting in Android thus provides a concrete visual depiction of startup behavior for analysis.

Interpreting Bootcharting Results in Android

The bootchart image from bootcharting in Android details crucial boot aspects:

• Process Timing: Highlights long-running or delayed-start processes that may block boot progress.
• CPU Load: Displays which processes consume most CPU during startup.
• Disk I/O: Shows heavy or sequential disk operations that slow boot.
• Idle Intervals: Identifies periods of low activity that may indicate forced waits or contention.
• Boot Milestones: Reveals timing of critical events like the end of the boot animation.
  For example, bootcharting in Android may expose lengthy Package Manager scanning, suggesting optimization or deferred processing to reduce boot time.

Common Bottlenecks Identified by Bootcharting in Android

Bootcharting often reveals bottlenecks such as:

• Slow initialization of device drivers
• Simultaneous startup of numerous services (etc init services)
• Lengthy scanning or verification of installed applications
• Prolonged Android system server initialization
• Aggressive app preloading causing CPU and disk spikes
  Addressing these can significantly reduce Android boot time.

Advanced Bootcharting and Tracing Techniques for Android

Beyond bootcharting, tools like Systrace offer in-depth kernel and framework tracing, capturing scheduling, CPU, and I/O events. For detailed analysis, see: Analyzing Android Boot Time with Bootchart and Systrace. Additional methods include kernel printk timestamps and I/O trace tools, which complement bootcharting by uncovering finer details.

Optimizing Boot Performance Using Bootcharting in Android

Insights from bootcharting inform optimization efforts such as:

• Tweaking init.rc scripts to disable or delay non-essential services
• Postponing background services until after boot completion
• Parallelizing independent startup processes
• Removing unnecessary components and drivers
• Streamlining hardware initialization routines
  Such adjustments, based on bootcharting data, lead to faster, smoother boot times.

Limitations and Troubleshooting for Bootcharting in Android

When performing bootcharting in Android, be mindful of:

• A small performance overhead (around 5–10%) affecting measured boot times
• Possible lack of writable /data/bootchart/ directory on production devices
• No native UI on Android; visualization requires extracting data and processing on a host machine
• Ensuring proper permissions, kernel flags, and buffer sizes to avoid incomplete logs

Bootcharting in Android Case Study

In one example, a sensor driver caused a 15-second init grab delay blocking subsequent steps. Package Manager scanning added 10 seconds, delaying UI appearance. Optimizing these areas reduced total boot time by 30%, balancing CPU and disk loads, and starting the boot animation sooner, improving user-perceived responsiveness.

Leveraging Cloud Devices for Bootcharting in Android

Testing bootcharting on real devices, including cloud-based Android phones offered by GeeLark, complements emulator-based profiling. GeeLark cloud phones run actual Android OS in the cloud, not emulators, providing authentic environments for testing boot performance.
GeeLark cloud phones don’t have a built-in bootchart init UI, but you can:

1. Enable bootchartd via ADB (e.g., setprop persist.bootchart.enable 1 or start the bootchartd service).
2. Reboot the cloud phone instance.
3. Pull the /data/bootchart/ logs using ADB.
4. Process logs locally with standard Bootchart tools.
   All steps must be done manually over ADB; no one-click profiling controls exist in GeeLark.
   Using real devices through GeeLark allows accurate boot profiling beyond emulator limitations, enhancing real-world analysis.
   By understanding and applying bootchart instructions android — from setup through data interpretation to optimization — developers can effectively diagnose boot delays and improve device responsiveness. Bootchart remains a foundational tool in the Android developer’s toolkit for boot performance, complemented by advanced tracing utilities like Systrace.
   For further details on bootcharting generating and usage, consult the official documentation: Android Bootchart README.
   Bootchart data extraction scripts and tools can be found here: android-bootchart GitHub repository.
   For deeper insight, see the analysis guide: Analyzing Android Boot Time with Bootchart and Systrace.
   References and Resources:

• Android Bootchart docs: android.googlesource.com
• Bootchart grab script: github.com/glandium/android-bootchart
• Boot time analysis guide: fudongbai.gitlab.io
• Overview of Android boot optimization tools: LinkedIn – Gopalakrishnan Mani
• Compare real device cloud testing to emulator simulation: check GeeLark Cloud Phone vs Android Emulator
  Utilizing cloud phone platforms like GeeLark, combined with bootcharting in Android, enhances your ability to profile and optimize real-device boot processes beyond traditional emulation, helping deliver better user experiences.

People Also Ask

What is bootchart?

Bootchart is a performance profiling tool that visualizes the Linux boot process. It logs:

• Startup Time: Tracks how long each process/service takes to load.
• Resource Usage: Charts CPU, disk, and memory consumption during boot.
• Dependencies: Maps relationships between system processes.
  Used by developers to optimize boot speed and identify bottlenecks in embedded systems, servers, or custom Linux distributions. Generates graphical timelines (PNG/SVG) for easy analysis. Enable via kernel parameters, then view charts with bootchartd or pybootchartgui.

What is the process of booting?

The booting process is how a computer starts up and loads the operating system. Here’s a simplified breakdown:

1. Power-On: Hardware initializes (POST – Power-On Self-Test).
2. BIOS/UEFI: Firmware checks hardware and locates the bootloader.
3. Bootloader: Loads the OS kernel (e.g., GRUB for Linux, Windows Boot Manager).
4. Kernel Initialization: OS kernel takes over, mounts filesystems, and starts critical services.
5. User Space: Launches login managers, desktop environments, and apps.
   Booting ensures hardware readiness and transitions control from firmware to the full OS. Variations exist for PCs, smartphones, and embedded systems.