如何在Linux(Ubuntu)下同时采集Chromium内核与用户态追踪并并列展示？

Absolutely! You can absolutely combine kernel-level and user-level tracing for Chromium on Ubuntu, and there are robust tools to make this work seamlessly. Let’s break this down into actionable steps, covering how to capture both types of traces and how to view them side by side.

User-Level Tracing with Chromium’s Built-In Tools #

Chromium comes with a powerful built-in tracing framework that captures user-space events like V8 execution, Blink rendering, and browser UI interactions. Here’s how to use it:

• Via the browser UI: Open chrome://tracing in Chromium, click "Record", select the categories you want to track (e.g., v8, blink, renderer), then start your test scenario. When done, stop recording and export the trace as a JSON file.
• Via command line: Launch Chromium with trace flags to start capturing immediately:

  chromium-browser --trace-config="*" --trace-startup=file --trace-startup-file=chromium_user_trace.json
  

  Adjust the --trace-config value to narrow down categories if you don’t need full coverage (e.g., "v8,blink.renderer").

Kernel-Level Tracing on Ubuntu #

For kernel-level events (system calls, process scheduling, memory operations, etc.), you have two primary tools: perf and eBPF-based tools like bpftrace.

Using perf #

perf is a standard Linux profiling tool that’s pre-installed on most Ubuntu systems. To trace kernel events for a running Chromium process:

1. Find your Chromium PID with pgrep chromium-browser.
2. Record kernel events along with call stacks:

   sudo perf record -p <CHROMIUM_PID> -e syscalls:* -g -- sleep <DURATION_IN_SECONDS>
   

   • -e syscalls:* captures all system call events (adjust to specific syscalls like syscalls:sys_enter_open if needed).
   • -g enables call stack capture for both user and kernel space.
3. View the raw trace with sudo perf report, or export it as a text file for further processing:

   sudo perf script -F time,pid,tid,comm,callchain > perf_kernel_trace.txt
   

Using eBPF (bpftrace) #

For more flexible, custom kernel tracing, bpftrace is excellent. Install it first with sudo apt install bpftrace. Here’s a simple example to trace sys_open calls from Chromium:

sudo bpftrace -e 'tracepoint:syscalls:sys_enter_open { if (pid == <CHROMIUM_PID>) { printf("[%d] %s opened: %s\n", pid, comm, args->filename); } }'

You can extend this to capture call stacks, track process scheduling, or monitor memory allocations—bpftrace’s scriptable nature lets you tailor traces to your exact needs.

Viewing Kernel and User Traces Side by Side #

The easiest way to visualize both trace types in a unified timeline is using Perfetto—Google’s open-source full-stack tracing tool that integrates seamlessly with Chromium and Linux kernel tracing.

Step-by-Step with Perfetto #

1. Install Perfetto on Ubuntu:

   sudo apt install perfetto
   

2. Create a trace configuration file (e.g., combined_trace_config.pbtxt) to specify both user and kernel sources:

   buffers {
     size_kb: 16384  # Adjust based on how much data you need to capture
   }
   
   # Capture Chromium user-space events
   data_sources {
     config {
       name: "com.google.chrome.trace"
       chrome_config {
         categories: "*"  # Narrow to specific categories if needed
       }
     }
   }
   
   # Capture Linux kernel events
   data_sources {
     config {
       name: "linux.ftrace"
       ftrace_config {
         ftrace_events: "sched/sched_switch"  # Track process scheduling
         ftrace_events: "syscalls/*"          # Track all system calls
         atrace_categories: "memory"          # Add more kernel categories as needed
       }
     }
   }
   

3. Start the trace:

   sudo perfetto -c combined_trace_config.pbtxt -o combined_trace.perfetto-trace
   

4. Launch Chromium and run your test scenario. When done, stop the Perfetto process (Ctrl+C).
5. Open the trace file in Perfetto’s UI: You can use Chromium’s built-in trace viewer by opening chrome://tracing and importing the .perfetto-trace file. Here, you’ll see a unified timeline with Chromium’s user-level events and kernel events aligned by timestamp—perfect for correlating user-space function calls with kernel activity.

Manual Integration (If You Don’t Want to Use Perfetto) #

If you prefer to work with raw files, you can:

• Export Chromium’s trace as JSON and perf’s trace as a text file.
• Write a simple script to align timestamps (note: Chromium uses monotonic time, while perf uses the same clock by default, so alignment should be straightforward).
• Use a custom visualization tool or even a spreadsheet to plot events side by side—though this is far less efficient than using Perfetto.

Key Notes #

• Root Access: Most kernel tracing tools require sudo privileges, since they access kernel-level data structures.
• Trace Overhead: Capturing full traces can add overhead to Chromium’s performance. Narrow down event categories to only what you need to minimize this.
• Perfetto is Your Friend: It’s the official tool for Chromium tracing and eliminates most of the hassle of combining kernel and user traces manually.

Hope this helps you get the combined tracing setup you need. Let me know if you run into any specific issues with tool configurations!

内容的提问来源于stack exchange，提问作者user32557