Complete Guide to Monitoring CPU Usage of iOS Apps with Keymob

1. Introduction

Keymob is a professional performance analysis tool for iOS devices, supporting real-time monitoring of overall system performance as well as the CPU usage of individual or multiple app processes. Through intuitive comparative graphs, developers can quickly pinpoint performance bottlenecks, analyze resource allocation in multitasking scenarios, and optimize app performance. This guide will walk you through the process of monitoring CPU usage on an iOS system or for a specific app and answer common questions.

2. Step-by-Step Instructions

1. Access the Performance Monitoring Interface

  • Connect the device: Launch the Keymob tool and connect your iOS device via USB or Wi-Fi.
  • Select the module: Click on the “Performance Charts” menu in the left sidebar to enter the real-time monitoring interface.

2. Enable CPU Monitoring Metrics

  • Select the metrics: In the top-right corner of the interface, use the “Metrics” dropdown to select the “CPU” option (as shown below).

  • Support for multiple metrics: If you’d like to monitor other metrics like memory usage or frame rate, you can select those as well.

    CPU Metrics Selection Interface

3. Select the Target App Process

  • Open the process selection: Click the “Select App” button in the center of the interface.
  • Search and filter:
    • In the popup window, enter the app name (e.g., “WeChat”) to perform a fuzzy search.
    • Select the processes you want to monitor (you can select multiple).
    • Compare with system-wide CPU: Select the “System Total CPU” option to display system-wide CPU usage alongside app process data.

4. Start Monitoring and Analyzing

  • Begin monitoring: Click the “Start” button in the top-right corner, and Keymob will begin collecting real-time CPU usage data.
  • Trigger actions: Perform actions on the device within the target app (such as scrolling a list or playing a video) to observe changes in CPU usage.
  • Data display:
    • A line graph will show the real-time CPU usage of each process and the system total.
    • The graph will display one minute of real-time data, and you can zoom in on the timeline when reopening the data to precisely locate high-load periods.

3. Data Interpretation and Common Questions

1. How to Interpret CPU Usage?

  • Single-core and multi-core:
    • For a 6-core device, the maximum theoretical CPU usage per process is 600% (i.e., all cores are fully utilized).
    • Example: If a process uses 200%, it means it is utilizing the resources of approximately two cores.
  • System total CPU: Reflects the overall load of the device, helping you determine if the issue lies with a specific app or insufficient system resources.

2. Is it normal for the total CPU usage to exceed 200%?

  • Explanation:
    • Modern iOS devices typically use multi-core CPUs (e.g., the A15 chip has 6 cores).
    • Total usage = sum of individual core usage, so the value can exceed 100%.
    • Example: If the total usage is 300%, it means each core is, on average, using 50%.
  • Performance judgment:
    • Short-term spikes are normal (e.g., when launching an app).
    • Persistent high load (e.g., sustained >80% total usage) may cause overheating and lag, and optimization is required.

4. Advanced Features and Tips

1. Multi-process Comparison

  • Use case: Monitor both a “game app” and a “music player” to analyze the resource impact of background processes.
  • Recommendation: Select 2-3 key processes to avoid chart clutter caused by selecting too many processes.

2. Data Saving and Playback

  • Save snapshots: Click the “Save” button to export the current monitoring data (with timeline markers) as a file.
  • Playback history: Use the “Performance History” module to load the file and replay the issue scenario.

5. Notes

  1. Monitoring Interference

    • Close other performance monitoring tools to avoid data conflicts.
    • Restart the device before testing to ensure that background processes are clean.

  2. Data Accuracy

    • When using a wireless connection, it’s recommended to disable automatic screen lock on the device to maintain a stable network.
    • Long-duration monitoring (>1 hour) may cause CPU throttling due to device overheating, and the data should be analyzed in conjunction with temperature information.

6. Conclusion

With Keymob’s CPU monitoring feature, developers can gain precise insights into app resource consumption under different scenarios, quickly pinpoint code hotspots or thread conflicts, and optimize performance. It’s recommended to combine memory, frame rate, and other metrics for multi-dimensional analysis and to regularly compare performance data across versions for continuous optimization of the user experience.