This is the ninth article in the Perfetto series, focusing on CPU information analysis in Perfetto. Perfetto provides far superior data visualization and analysis capabilities compared to Systrace. Understanding CPU-related information is the foundation for locating performance bottlenecks and analyzing power consumption issues.

The goal of this series is to examine the overall operation of the Android system from a brand new graphical perspective through the Perfetto tool, while also providing a new way to learn the Framework. Perhaps you’ve read many source code analysis articles but always feel confused by the complex call chains or can’t remember specific execution flows. Through Perfetto, by visualizing these processes, you may gain a deeper and more intuitive understanding of the system.

This is the eighth article in the Perfetto series, providing an in-depth introduction to the Vsync mechanism in Android and its representation in Perfetto. The article will analyze how the Android system performs frame rendering and composition based on Vsync signals from Perfetto’s perspective, covering core concepts such as Vsync, Vsync-app, Vsync-sf, and VsyncWorkDuration.

With the popularization of high refresh rate screens, understanding the Vsync mechanism has become increasingly important. This article uses 120Hz refresh rate as the main narrative thread to help developers understand the working principles of Vsync in modern Android devices, and how to observe and analyze Vsync-related performance issues in Perfetto.

Note: This article is based on Android 16’s latest architecture and implementation

This is the seventh article in the Perfetto series, focusing on MainThread (UI Thread) and RenderThread, the two most critical threads in any Android application. This article will examine the workflow of MainThread and RenderThread from Perfetto’s perspective, covering topics such as jank, software rendering, and frame drop calculations.

As Google officially promotes Perfetto as the replacement for Systrace, Perfetto has become the mainstream choice in performance analysis. This article combines specific Perfetto trace information to help readers understand the complete workflow of MainThread and RenderThread, enabling you to:

• Accurately identify key trace tags: Understand the roles of critical threads like UI Thread and RenderThread
• Understand the complete frame rendering process: Every step from Vsync signal to screen display
• Locate performance bottlenecks: Quickly find the root cause of jank and performance issues through trace information

This is the sixth article in the Android Perfetto series. It focuses on the 120Hz refresh rate, which has now become a standard for Android flagship devices. We will discuss the advantages and challenges of high refresh rates and analyze how 120Hz works from a system perspective.

Over the past few years, mobile display technology has evolved from 60Hz to 90Hz and now commonly to 120Hz. This evolution brings not only a smoother visual experience but also new requirements for system architecture and app development. Using Perfetto, we can gain a clearer understanding of frame rendering and performance on high-refresh-rate devices.

This article introduces Choreographer, a class that App developers may not frequently encounter but is critically important in the Android Framework rendering pipeline. We will cover the background of its introduction, a brief overview, partial source code analysis, its interaction with MessageQueue, its application in APM (Application Performance Monitoring), and some optimization ideas for Choreographer by mobile phone manufacturers.

The introduction of Choreographer is mainly to cooperate with Vsync to provide a stable Message processing timing for upper-layer application rendering. When the Vsync signal arrives, the system controls the timing of each frame’s drawing operation by adjusting the Vsync signal cycle. Currently, the screen refresh rate of mainstream mobile phones has reached 120Hz, which means refreshing once every 8.3ms. The system adjusts the Vsync cycle accordingly to match the screen refresh frequency. When each Vsync cycle arrives, the Vsync signal wakes up the Choreographer to execute the application’s drawing operation. This is the main purpose of introducing Choreographer. Understanding Choreographer can also help application developers deeply understand the operating principle of each frame, and at the same time deepen their understanding of core components such as Message, Handler, Looper, MessageQueue, Input, Animation, Measure, Layout, and Draw. Many APM (Application Performance Monitoring) tools also utilize the combination mechanisms of Choreographer (via FrameCallback + FrameInfo), MessageQueue (via IdleHandler), and Looper (via custom MessageLogging) for performance monitoring. After deeply understanding these mechanisms, developers can conduct performance optimization more specifically and form systematic optimization ideas.

This is the fourth article in the Perfetto series. It explains how to use trace_processor_shell to open large trace files (often exceeding 2GB). In practice, we frequently encounter massive traces that the browser-based ui.perfetto.dev cannot open due to browser memory constraints. To solve this, we use the official trace_processor_shell tool to power the analysis from your local machine.

This is the second article in the Android App ANR series, focusing on ANR analysis methodology and key logs. The series includes:

1. Android App ANR Series 1: Understanding Android ANR Design Philosophy
2. Android App ANR Series 2: ANR Analysis Methodology and Key Logs
3. Android App ANR Series 3: ANR Case Studies

This is the second article in the Android App ANR series, focusing on ANR analysis methodology and key logs. The series includes:

1. Android App ANR Series 1: Understanding Android ANR Design Philosophy
2. Android App ANR Series 2: ANR Analysis Methodology and Key Logs
3. Android App ANR Series 3: ANR Case Studies

This is the third article in the Perfetto series. After introducing what Perfetto is and how to capture traces, this article focuses on how to navigate the web interface and interpret the complex information presented after opening a trace.

The previous article Android Perfetto Series 1: Introduction to Perfetto introduced what Perfetto is. This article will provide a brief guide on how to capture Perfetto traces.

This is the first article in the Perfetto series. It provides a brief introduction to the tool, including its history, development, and capabilities.

With Google announcing the deprecation of Systrace in favor of Perfetto, Perfetto has essentially replaced Systrace in my daily workflow. Major manufacturers like OPPO and vivo have also transitioned to Perfetto. Many developers new to Android performance optimization find Perfetto’s complex interface and features overwhelming, which is why I’ve decided to re-present my previous Systrace articles using Perfetto.

With Google announcing the deprecation of Systrace in favor of Perfetto, Perfetto has essentially replaced Systrace in my daily workflow. Major manufacturers like OPPO and vivo have also transitioned to Perfetto. Many developers new to Android performance optimization find Perfetto’s complex interface and features overwhelming, which is why I’ve decided to re-present my previous Systrace articles using Perfetto.

Currently, the “Knowledge Planet” (ZSXQ) is a paid community. The income mainly goes towards blog server costs and buying cat food for my cat, Douzi. It also serves as my motivation to keep updating the blog. If you find the content helpful, consider joining to support the work! Thank you very much!

The community is named The Performance, a circle for sharing Android performance optimization. I am the host—an Android performance developer at a top-tier smartphone manufacturer in China with years of experience in performance, power consumption analysis, and case studies. This community provides a one-stop-shop for performance knowledge, covering fundamentals, methodologies, tools, and valuable real-world case analyses.

A while ago, a certain App became very popular because it exploited Android system vulnerabilities to gain system permissions and did a lot of things. I wanted to see what these Apps did after gaining system permissions by exploiting system vulnerabilities, hence this article. Due to hasty preparation, some Code was not looked at carefully. Interested students can research it themselves and discuss more. The corresponding articles and Code links are below:

1. Deep Blue Insight: The Most “Unpardonable” Vulnerabilities of 2022
2. XXX apk embedded privilege escalation code and dynamic delivery dex analysis
3. History of Android Deserialization Vulnerability Attack and Defense

Regarding how this App obtained these system permissions, History of Android Deserialization Vulnerability Attack and Defense explains it very clearly, so I won’t repeat it here. I am not a security expert either, but I suggest everyone read this article a few times.

Recently, there was a major buzz around an Android app that exploited a system vulnerability to gain system-level privileges. I wanted to see exactly what an app does once it breaks out of its sandbox and gains that level of control. This led to this article. Due to time constraints, some code wasn’t examined in detail. Interested readers can study it themselves and discuss further. The corresponding articles and code links are below:

1. Deep Blue Insight: 2022’s Most “Unforgivable” Vulnerability
2. XXX apk Embedded Privilege Escalation Code and Dynamic Dex Delivery Analysis
3. History of Android Deserialization Vulnerability Attacks and Defenses

Regarding how this app obtained system permissions, History of Android Deserialization Vulnerability Attacks and Defenses explains it clearly, so I won’t elaborate further. I’m not a security expert, but I recommend reading this article multiple times.

On Friday, March 25, 2022, at 9 PM, “The Performance” Knowledge Planet held its first online “Tea Talk.” We were joined by 3 planet hosts, 5 guest experts, and over 50 members. Thank you all for coming!

While we expected to wrap up in an hour, we ended up chatting for over two and a half hours—our introductions alone took an hour! Our community spans the entire Android ecosystem: from App-tier experts to System-level gurus at major smartphone manufacturers, silicon companies, and EV startups. Each introduction naturally evolved into deep dives into industry trends and company-specific insights.

We plan to hold these regularly with clearer themes and more guests. To protect the privacy of our members, we did not record the session. The following text is a reconstructed summary of our discussion.

This is the third article in the “Systrace Thread CPU State Analysis Tips” series. It focuses on the Sleep and Uninterruptible Sleep states in Systrace—their causes, troubleshooting, and optimization. These states are major performance inhibitors and are often difficult to diagnose without a systematic approach.

The goal of this series is to use Systrace to view the Android system from a different perspective and to learn the Framework through visualization. While reading Framework source code can be difficult to remember, seeing the flow in Systrace can lead to deeper understanding. You can find the complete Systrace Basics and Action Series here.

This is the second article in the “Systrace Thread CPU State Analysis Tips” series. It analyzes the causes of the “Running” state in Systrace and provides optimization strategies for when Running segments are excessively long.

The goal of this series is to use Systrace to view the Android system from a different perspective and to learn the Framework through visualization. While reading Framework source code can be difficult to remember, seeing the flow in Systrace can lead to deeper understanding. You can find the complete Systrace Basics and Action Series here.

This is the first article in the “Systrace Thread CPU State Analysis Tips” series. It analyzes the causes of the “Runnable” state in Systrace and provides optimization strategies for when Runnable segments are excessively long.

The goal of this series is to use Systrace to view the Android system from a different perspective and to learn the Framework through visualization. While reading Framework source code can be difficult to remember, seeing the flow in Systrace can lead to deeper understanding. You can find the complete Systrace Basics and Action Series here.

2021 has passed. Taking advantage of the New Year holiday, I’d like to look back at the year. This will be a casual review—writing whatever comes to mind. 2021 for me was marked by becoming a father, changing jobs (including a boring period of working from home), and making new friends. Overall, it was a pretty good year.

However, in terms of personal growth, I feel like I might have stagnated or even regressed, which is a bit alarming. Learning is like rowing upstream; if you don’t move forward, you fall back. 2022 needs to be a year of deep cultivation. I hope to progress together with everyone reading this.

I’ve also tallied some data related to my technical sharing, shared my income from these platforms, and listed some hardware and software I recommend. Feel free to take a look.

Recently, I read a new book: Building Smooth Android Apps (JD link: https://item.jd.com/10035215362170.html). I bought it because of the title, and after reading it, I felt it was necessary to write an article so that colleagues who haven’t bought it yet can understand what it’s about.

My personal suggestion is: if you are an experienced developer, I don’t recommend buying it. This book doesn’t go into much depth on principles and doesn’t offer a comprehensive overview of Android smoothness. If you are a beginner, it’s decent for broadening your horizons and identifying gaps in your knowledge, but it’s still a bit lacking for a deep understanding of Android smoothness.

I say this because the book doesn’t focus much on performance or smoothness. It lacks deep theoretical parts. Instead, a large portion is dedicated to static code analysis, using Android Studio Profiler, App architecture, app stay-alive techniques, network performance optimization, APK size optimization, app power consumption, etc. These topics are covered briefly and at a shallow level.

When discussing Android performance, Jank, Responsiveness, and ANR are usually grouped together because their causes are similar. They are simply categorized based on severity: Jank, Slow Response, and ANR. We can define “Broad Jank” to include all three. If a user reports that a phone or App is “stuttering,” they are likely referring to Broad Jank, and we must identify which specific issue is occurring.

If it’s stuttering during animation or list scrolling, we define it as Narrow Jank (referred to as Jank). If it’s slow app startup, slow screen wake-up, or slow scene switching, we define it as Slow Responsiveness (referred to as Slow). If it’s an ANR, it’s an Application Not Responding issue. Each situation requires different analysis and resolution methods.

Furthermore, within Apps or manufacturers, Jank, Responsiveness, and ANR have individual metrics like Frame Drop Rate, Startup Speed, and ANR Rate. Mastering the analysis and optimization of these issues is crucial for developers.

This is the third article in the Responsiveness series, focusing on extended knowledge when using Systrace to analyze app responsiveness, including startup speed testing, log interpretation, state analysis, and third-party startup libraries.

When discussing Android performance, Jank, Responsiveness, and ANR are usually grouped together because their causes are similar. They are simply categorized based on severity: Jank, Slow Response, and ANR. We can define “Broad Jank” to include all three. If a user reports that a phone or App is “stuttering,” they are likely referring to Broad Jank, and we must identify which specific issue is occurring.

If it’s stuttering during animation or list scrolling, we define it as Narrow Jank (referred to as Jank). If it’s slow app startup, slow screen wake-up, or slow scene switching, we define it as Slow Responsiveness (referred to as Slow). If it’s an ANR, it’s an Application Not Responding issue. Each situation requires different analysis and resolution methods.

Furthermore, within Apps or manufacturers, Jank, Responsiveness, and ANR have individual metrics like Frame Drop Rate, Startup Speed, and ANR Rate. Mastering the analysis and optimization of these issues is crucial for developers.

This is the second article in the Responsiveness series, using Android App Cold Start as an example to explain how to use Systrace for analysis.

When discussing Android performance, Jank, Responsiveness, and ANR are usually grouped together because their causes are similar. They are simply categorized based on severity: Jank, Slow Response, and ANR. We can define “Broad Jank” to include all three. If a user reports that a phone or App is “stuttering,” they are likely referring to Broad Jank, and we must identify which specific issue is occurring.

If it’s stuttering during animation or list scrolling, we define it as Narrow Jank (referred to as Jank). If it’s slow app startup, slow screen wake-up, or slow scene switching, we define it as Slow Responsiveness (referred to as Slow). If it’s an ANR, it’s an Application Not Responding issue. Each situation requires different analysis and resolution methods.

Furthermore, within Apps or manufacturers, Jank, Responsiveness, and ANR have individual metrics like Frame Drop Rate, Startup Speed, and ANR Rate. Mastering the analysis and optimization of these issues is crucial for developers.

This is the first article in the Responsiveness series, focusing on theoretical knowledge, including an overview of performance engineering, key responsiveness concepts, and analysis methodologies.

Different people have different understandings of smoothness (jank/dropped frames) and different perceptions of jitter thresholds. Therefore, before starting this series, it is necessary to clarify the content to avoid misunderstandings. Here are some basic explanations:

1. For mobile users, jank encompasses many scenarios: dropped frames when scrolling lists, excessive white screen during app startup, slow screen wake-up when pressing the power button, unresponsive interface followed by a crash, no response when clicking an icon, incoherent window animations, lagging touch response, or stuttering when entering the desktop after a reboot. These scenarios differ slightly from what developers understand as “jank.” Developers categorize these more finely, which is a cognitive gap between developers and users that must be noted when handling feedback from users or testers.
2. For developers, the above scenarios fall into three major categories: Smoothness (dropped frames in lists, incoherent animations, stuttering desktop entry), Responsiveness (long startup white screens, slow screen wake-up, lagging touch), and Stability (unresponsive interface/crashes, no response to icon clicks). This classification is used because each category requires different analysis methods and steps. Quickly identifying the category is crucial.
3. Technically, Smoothness, Responsiveness, and Stability (ANR) all feel like “jank” to users because their underlying principles are identical: the main thread’s Message exceeds its processing deadline. They are simply categorized by different timeout thresholds. Understanding these problems requires knowledge of basic system operation mechanisms, which this article will introduce.
4. This series primarily analyzes smoothness-related issues. Responsiveness and stability will be covered in dedicated articles. Understanding smoothness first will make analyzing responsiveness and stability much easier.
5. This series focuses on using Systrace (Perfetto) for analysis. Systrace is our entry point because many factors affect smoothness—some within the app itself and others within the system. Systrace (Perfetto) provides a holistic view of the system’s operation during the problem, helping us initially pinpoint the root cause.

Different people have different understandings of smoothness (jank/dropped frames) and different perceptions of jitter thresholds. Therefore, before starting this series, it is necessary to clarify the content to avoid misunderstandings. Here are some basic explanations:

1. For mobile users, jank encompasses many scenarios: dropped frames when scrolling lists, excessive white screen during app startup, slow screen wake-up when pressing the power button, unresponsive interface followed by a crash, no response when clicking an icon, incoherent window animations, lagging touch response, or stuttering when entering the desktop after a reboot. These scenarios differ slightly from what developers understand as “jank.” Developers categorize these more finely, which is a cognitive gap between developers and users that must be noted when handling feedback from users or testers.
2. For developers, the above scenarios fall into three major categories: Smoothness (dropped frames in lists, incoherent animations, stuttering desktop entry), Responsiveness (long startup white screens, slow screen wake-up, lagging touch), and Stability (unresponsive interface/crashes, no response to icon clicks). This classification is used because each category requires different analysis methods and steps. Quickly identifying the category is crucial.
3. Technically, Smoothness, Responsiveness, and Stability (ANR) all feel like “jank” to users because their underlying principles are identical: the main thread’s Message exceeds its processing deadline. They are simply categorized by different timeout thresholds. Understanding these problems requires knowledge of basic system operation mechanisms, which this article will introduce.
4. This series primarily analyzes smoothness-related issues. Responsiveness and stability will be covered in dedicated articles. Understanding smoothness first will make analyzing responsiveness and stability much easier.
5. This series focuses on using Systrace (Perfetto) for analysis. Systrace is our entry point because many factors affect smoothness—some within the app itself and others within the system. Systrace (Perfetto) provides a holistic view of the system’s operation during the problem, helping us initially pinpoint the root cause.

Different people have different understandings of smoothness (jank/dropped frames) and different perceptions of jitter thresholds. Therefore, before starting this series, it is necessary to clarify the content to avoid misunderstandings and help everyone approach these articles with the right questions. Here are some basic explanations:

1. For mobile users, jank encompasses many scenarios: dropped frames when scrolling lists, excessive white screen during app startup, slow screen wake-up when pressing the power button, unresponsive interface followed by a crash, no response when clicking an icon, incoherent window animations, lagging touch response, or stuttering when entering the desktop after a reboot. These scenarios differ slightly from what developers understand as “jank.” Developers categorize these more finely, which is a cognitive gap between developers and users that must be noted when handling feedback from users or testers.
2. For developers, the above scenarios fall into three major categories: Smoothness (dropped frames in lists, incoherent animations, stuttering desktop entry), Responsiveness (long startup white screens, slow screen wake-up, lagging touch), and Stability (unresponsive interface/crashes, no response to icon clicks). This classification is used because each category requires different analysis methods and steps. Quickly identifying the category is crucial.
3. Technically, Smoothness, Responsiveness, and Stability (ANR) all feel like “jank” to users because their underlying principles are identical: the main thread’s Message exceeds its processing deadline. They are simply categorized by different timeout thresholds. Understanding these problems requires knowledge of basic system operation mechanisms, which this article will introduce.
4. This series primarily analyzes smoothness-related issues. Responsiveness and stability will be covered in dedicated articles. Understanding smoothness first will make analyzing responsiveness and stability much easier.
5. This series focuses on using Systrace (Perfetto) for analysis. Systrace is our entry point because many factors affect smoothness—some within the app itself and others within the system. Systrace (Perfetto) provides a holistic view of the system’s operation during the problem, helping us initially pinpoint the root cause.

This is the fifth article in the Systrace series, primarily providing a brief introduction to the workflow of SurfaceFlinger. It covers several important threads within SurfaceFlinger, including Vsync signal interpretation, app buffer display, and jank detection. Since Vsync has already been covered in Systrace Basics - Vsync Explained and Detailed Explanation of Android Rendering Mechanism Based on Choreographer, it won’t be discussed in detail here.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

This is the twelfth article in the Systrace series, primarily providing a brief introduction to the CPU information area (Kernel) in Systrace. It covers how to view CPU-related information output by the Kernel module, including CPU frequency, scheduling, frequency locking, and core locking.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

This is the eleventh article in the Systrace series, providing a brief introduction to Triple Buffer within Systrace. It covers how to identify jank in Systrace, perform preliminary localization and analysis, and explains the impact of Triple Buffer on performance.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

This is the tenth article in the Systrace series, primarily providing a brief introduction to Binder and lock information in Systrace. It covers the basic situation of Binder, the representation of Binder communication in Systrace, how to view Binder information, and analysis of lock contention in SystemServer.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

The content of this blog mainly focuses on Android development and optimization-related topics, including the use of performance tools, Android App optimization knowledge, Android Framework explanations, and performance theory. Here is an organized directory for your reference. You can choose the parts you are interested in. This directory includes not only blog content but also some of my answers on Zhihu or the Knowledge Planet - The Performance. This directory lists my original blog posts. Additionally, I have collected some excellent articles in Must-Knows for Android Performance Optimization, which I update periodically.

This is the seventh article in the Systrace series, primarily introducing the Vsync mechanism in Android. This article examines the display of each frame in the Android system from the perspective of Systrace. Vsync is a critical mechanism in Systrace. Although invisible and intangible when operating a phone, we can see in Systrace how the Android system, guided by Vsync signals, orderly performs rendering and composition for each frame, ensuring stable frame rates.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

This is the ninth article in the Systrace series, primarily introducing the MainThread and RenderThread in Android Apps—commonly known as the Main Thread and Rendering Thread. This article examines their workflows from the perspective of Systrace and covers related topics: jank, software rendering, and dropped frame calculation.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

This is the sixth article in the Systrace series, primarily providing a brief introduction to Input in Systrace. It covers the Input workflow, how Input information is represented in Systrace, and how to combine Input info to analyze related performance issues.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

When an Android app moves to the background, it’s not unusual for it to keep performing work as long as the process isn’t killed—that’s just the nature of Android. However, some apps continue to run “zombie animations”—animations that are completely invisible to the user yet consume precious CPU cycles and battery. When users discover this, the result is often a manual kill, an OS-level background restriction, or an outright uninstallation.

Most developers never notice this issue. However, if you use Systrace regularly, you can easily spot it. If you open several apps, return to the home screen, and capture a trace while swiping between launcher pages, you’ll often see background apps still firing animation callbacks.

“Zombie animations” occur when an app, despite being invisible, continues to push CALLBACK_ANIMATION requests to the Choreographer. Every app is different, but the root cause is usually a missing pause or stop call.

This article introduces Choreographer, a class that app developers rarely encounter but is crucial in the Android Framework rendering pipeline. It covers the background of Choreographer‘s introduction, an overview, source code analysis, its relationship with MessageQueue, its use in APM, and optimization ideas from mobile manufacturers.

Choreographer was introduced to coordinate with Vsync, providing a stable timing for handling Messages in app rendering. When Vsync arrives, the system adjusts the Vsync signal period to control the timing of drawing operations for each frame. Most phones currently have a 60Hz refresh rate (16.6ms). To match this, the system sets the Vsync period to 16.6ms, waking Choreographer every period to perform app drawing—this is its primary role. Understanding Choreographer also helps developers grasp the principles of frame execution and deepens knowledge of Message, Handler, Looper, MessageQueue, Measure, Layout, and Draw.

This article was inspired by a real-world bug I encountered. While the issue itself wasn’t particularly “hard,” the analysis process—the tools used, the investigative logic, and some clever tips I learned from a colleague—made it a perfect candidate for a case study.

I’ve used a variety of tools mentioned in my Android Performance Optimization Methodology, including:

• Reproduction Video
• Event Log
• AS Source/Debug
• AS Profiler
• Systrace
• Dumpsys
• Unix ps utility

My goal is to document this process for myself and to share a universal troubleshooting workflow that might help others. If you have your own debugging tips, feel free to join our discussion group!

In the Overview of Jank and Frame Drops in Android - System Layer article, we listed causes of jank originating from the system. In this article, we focus on causes stemming from the App itself. When you encounter lag, before blaming the phone manufacturer, consider if it’s the App’s own inefficiency.

In the Overview of Jank and Frame Drops in Android - Application Layer article, we listed causes of jank originating from the app itself. In this article, we focus on causes stemming from the Android platform. Due to differences in hardware performance, feature implementations, and engineering capabilities among Android OEMs, system quality varies significantly. Here, we’ll categorize performance issues caused by system hardware and software.

Jank issues in Android are taken very seriously by both smartphone manufacturers and app developers. Internal teams, often called “Performance” or “Stability” groups, are typically dedicated to optimizing these experiences.

Currently, excellent third-party performance monitoring tools like Tencent’s Matrix are available. Phone manufacturers also have proprietary solutions. Since they can modify source code and bypass certain permission hurdles, manufacturers can access deeper system data, making analysis more efficient.

Android Activities have several critical launch modes: standard, singleTop, singleTask, and singleInstance. Each serves a specific architectural purpose. In this post, I’ll demonstrate their behaviors using a demo and visualizing the Activity Stack at each step.

An Activity Stack is a Last-In-First-Out (LIFO) data structure. Paying attention to the “Stack Content” column in the examples below will help you grasp how these modes differ in practice.

The demo code is available on GitLab: AndroidLaunchModeTest.

Android Activities have several critical launch modes: standard, singleTop, singleTask, and singleInstance. Each serves a specific architectural purpose. In this post, I’ll demonstrate their behaviors using a demo and visualizing the Activity Stack at each step.

An Activity Stack is a Last-In-First-Out (LIFO) data structure. Paying attention to the “Stack Content” column in the examples below will help you grasp how these modes differ in practice.

The demo code is available on GitLab: AndroidLaunchModeTest.

Hardware Acceleration vs Software AccelerationMany people confuse hardware acceleration and Hardware Layer in Android, thinking that enabling hardware acceleration means enabling Hardware Layer. So before discussing Hardware Layer, let’s first talk about hardware acceleration. For more detailed a...

Hardware Acceleration vs. Software AccelerationMany people confuse “hardware acceleration” with “Hardware Layer” in Android, assuming that enabling hardware acceleration means enabling Hardware Layer. So before we talk about Hardware Layer, let’s first talk about hardware acceleration. For more d...

This is the second article in the Systrace series, primarily explaining the prerequisites for analyzing Systrace. With these prerequisites, analyzing Systrace will be more effective, allowing you to identify issues faster and more efficiently.

This article introduces how to view thread states in Systrace, how to analyze thread wakeup information, how to interpret data in the information panel, and common shortcuts. By studying this article, you will gain an understanding of process and thread-related information and know how to extract key information from complex Systrace traces.

This is the fourth article in the Systrace series, primarily providing a brief introduction to SystemServer. It covers several important threads within SystemServer. Since Input and Binder are particularly critical, they are discussed separately and won’t be covered in detail here.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

This is the first article in the Systrace series, primarily providing a brief introduction to Systrace, its basic usage, how to interpret Systrace traces, and how to analyze phenomena in Systrace in conjunction with other tools.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

This is the third article in the Systrace series, explaining why 60 FPS is constantly emphasized. 60 FPS is a software concept, distinct from the 60Hz mentioned in screen refresh rates. For further context, refer to: A New Smooth Experience: A Talk on 90Hz.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

As Systrace becomes increasingly feature-rich, combined with Android version iterations, the previous Systrace series tutorials have become somewhat outdated. Additionally, as my own skills have improved, I’ve been able to extract more information from Systrace, which has been very helpful in solving various performance issues. I need to document these skills to enhance my summarization and organization abilities, and if it helps those who read these articles, that would be excellent.

The purpose of this series is to view the overall operation of the Android system from a different perspective using Systrace, while also providing an alternative angle for learning the Framework. Perhaps you’ve read many articles about the Framework but can never remember the code, or you’re unclear about the execution flow. Maybe from Systrace’s graphical perspective, you can gain a deeper understanding.

High-refresh-rate screens have been common on PCs for years, but they’ve only recently made their way to Android. While the Razer Phone introduced a 120Hz screen last year to a quiet reception, I believe the 90Hz screens on the Nubia Red Magic 3 and OnePlus 7 Pro represent the current “sweet spot...

The PhenomemonUsers reported that scrolling through lists, whether on the home screen or in settings, occasionally felt jittery or “shaky.” This issue wasn’t universal but affected a subset of users consistently once it appeared. For those in a hurry, you can skip to the “The Culprits” and “Self-...

PhenomenonSome users reported that while scrolling on the phone, the list would jitter. This happens when scrolling on the desktop or settings (as long as it is scrollable), but this is not reproducible for everyone; it appears for some users, but not for others. Onlookers can scroll directly to ...

It’s often said that the overall iOS experience is superior to Android. This is partly due to third-party software quality (iOS versions are often more polished) and partly due to Apple’s tight control over its ecosystem. To get on the App Store, you must pass rigorous reviews.

Today, we’ll discuss a major differentiator between iOS and Android: the StartingWindow (colloquially, the Splash Screen). While both systems have them, their implementations vary wildly. iOS requires a StartingWindow—usually a static image—that displays immediately upon an icon tap with zero delay. Android, being open, allows developers to customize, disable, or even make the StartingWindow transparent.

Preface

This article serves as a set of learning notes documenting the basic workflow of RenderThread in hwui as introduced in Android 5.0. Since these are notes, some details might not be exhaustive. Instead, I aim to walk through the general flow and highlight the key stages of its operation for future reference when debugging.

The image below shows a Systrace capture of the first Draw operation by the RenderThread during an application startup. We can trace the RenderThread workflow by observing the sequence of events in this trace. If you are familiar with the application startup process, you know that the entire interface is only displayed on the phone after the first drawFrame is completed. Before this, the user sees the application’s StartingWindow.

Note: This content is outdated. Please refer to the new Systrace Series Articles for updated information.

This is the first article in the Android Performance Optimization Tools series. This series mainly introduces the tools used during the Android performance optimization process, how to use these tools to discover problems, and how to solve them. In terms of performance optimization, Android provides many performance tools for everyone to use. Following our consistent “discover problem - solve problem” thinking, discovering the problem is the most important part. Trying to solve a problem without first identifying it properly often leads to half the effort for twice the result.

In this article, we’ll start with a brief introduction to the Systrace tool.

Introduction to Systrace

Systrace is a performance data sampling and analysis tool introduced in Android 4.1. It helps developers collect execution information from key Android subsystems (such as SurfaceFlinger, WindowManagerService, and other critical Framework modules, services, and the View system), allowing for a more intuitive analysis of system bottlenecks and performance improvements.

Systrace’s capabilities include tracking system I/O operations, kernel workqueues, CPU load, and the health of various Android subsystems. On the Android platform, it’s composed of three main parts:

• Kernel Space: Systrace leverages the ftrace feature in the Linux Kernel. Therefore, to use Systrace, the relevant ftrace modules in the kernel must be enabled.
• Data Collection: Android defines a Trace class that applications can use to output statistical information to ftrace. Additionally, the atrace program in Android reads statistical info from ftrace and passes it to data analysis tools.
• Data Analysis Tools: Android provides systrace.py (a Python script located in Android SDK directory/platform-tools/systrace that calls atrace internally) to configure data collection (such as tags, output filename, etc.), collect ftrace statistics, and generate a resulting HTML file for user viewing. Essentially, Systrace is a wrapper around the Linux Kernel’s ftrace. Applications need to utilize the Trace class provided by Android to use Systrace.

Official documentation and usage for Systrace can be found here: Systrace