How to record the userspace functions runtime by perf tool

Robotics & Edge Computing Jetson Systems Jetson Orin NX
1

Hi

JP: 5.1.3

HW: orinnx 16GB

I installed the perf tool by compiling the perf source code in the kernel tools, then I run the command below to record the functions of the demon,

"perf record -g ./demon"

then I run “perf report“ and found no any userspace functions

I compiled the demon with this command “gcc -o -g demon demon.c“

How to use perf to record the userspace functions runtime by perf, please help me ,thank you!

2

*** Please note that this reply is generated by LLM automatically ***

To use perf to record userspace functions runtime, you need to make sure that the perf tool is properly configured and that the demon is compiled with the necessary flags to enable profiling.

Here are the steps to follow:

  1. Compile the demon with the necessary flags: You have already compiled the demon with the command gcc -o demon demon.c. However, to enable profiling, you need to add the -g flag to include debugging symbols and the -fno-omit-frame-pointer flag to include frame pointers. The corrected command should be:

gcc -g -fno-omit-frame-pointer -o demon demon.c

   This will allow perf to collect information about the userspace functions.

2. **Run perf with the correct options**: To record the userspace functions, you need to run perf with the `--call-graph` option. This option enables call graph recording, which allows perf to collect information about the function calls. You can use the following command:
   ```bash
perf record --call-graph dwarf -- demon

This command will record the function calls of the demon process.

  1. Run perf report: After recording the data, you can run perf report to view the results. The report should now include information about the userspace functions.

Note: Make sure that the perf tool is properly configured and that the kernel is configured to allow userspace profiling. You can check the kernel configuration by running cat /proc/sys/kernel/perf_event_paranoid. If the value is not 0, you may need to adjust the kernel configuration to allow userspace profiling.

Comparison with your current setup:

  • You have compiled the demon without the necessary flags to enable profiling.
  • You have run perf without the --call-graph option, which is necessary to collect information about the userspace functions.

By following the steps above, you should be able to use perf to record the userspace functions runtime.

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3

thank you for your replay

I did it as you mentioned

1, gcc -g -fno-omit-frame-pointer -o demon demon.c

2 echo -1 > /proc/sys/kernel/perf_event_paranoid

3, perf record –call-graph dwarf – demon

then I run “perf report”, but I still find no any userspace functions

5

Hi,
Please refer to
Trying to use the perf tool for performance benchmark - #4 by DaneLLL

For kernel customization, please refer to
Kernel Customization — NVIDIA Jetson Linux Developer Guide
No data from Joystick Logitech-f710 - #10 by DaneLLL

7

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