https://github.com/findstr/lua-perf
A perf tool for C and Lua hybrid code
https://github.com/findstr/lua-perf
Last synced: 10 months ago
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A perf tool for C and Lua hybrid code
- Host: GitHub
- URL: https://github.com/findstr/lua-perf
- Owner: findstr
- License: mit
- Created: 2023-08-30T02:11:51.000Z (almost 3 years ago)
- Default Branch: main
- Last Pushed: 2024-03-22T03:13:17.000Z (over 2 years ago)
- Last Synced: 2025-09-07T08:41:14.239Z (11 months ago)
- Language: Rust
- Size: 101 KB
- Stars: 72
- Watchers: 3
- Forks: 7
- Open Issues: 0
-
Metadata Files:
- Readme: README.en.md
- License: LICENSE
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README
# lua-perf
[](./README.md)
`lua-perf` is a performance profiling tool implemented based on `eBPF`, currently supporting `Lua 5.4`.
## Features
- Provides performance analysis for mixed `C` and `Lua` code, as well as pure `C` code.
- Uses stack sampling technique with minimal performance impact on the target process, making it suitable for production environments.
- Performs stack backtracing in the kernel space using `eh-frame`, eliminating the need for the target process to use the `-fno-omit-frame-pointer` option to preserve stack frame pointers.
## Requirements
To use `lua-perf`, make sure you meet the following requirements:
- The installed kernel version needs to be `5.17` or above.
## Generating Flame Graphs
To generate flame graphs, you need to use `lua-perf` in conjunction with the [FlameGraph](https://github.com/brendangregg/FlameGraph.git) tool. Here's how you can do it:
1. First, run the command `sudo lua-perf -p -f ` to sample the call stacks of the target process and generate a `perf.fold` file in the current directory. `` is the process ID of the target process, which can be a process inside a Docker container or a process on the host machine. `` is the stack sampling frequency, with a default value of `1000` (1000 samples per second).
2. Next, convert the `perf.fold` file to a flame graph by running `./FlameGraph/flamegraph.pl perf.folded > perf.svg`.
3. Finally, you will find the generated flame graph, `perf.svg`, in the current directory.
Here's an example flame graph:
## Logging
In the BPF program, bpf_trace_printk is used to print logs. If you suspect any abnormalities in the performance sampling, you can view the logs using the following commands:
```
sudo mount -t tracefs nodev /sys/kernel/tracing
sudo cat /sys/kernel/debug/tracing/trace_pipe
These commands will help you access the logs and view them. If you have any further questions, feel free to ask.
```
## Known Issues
`lua-perf` currently has the following known issues:
- Lack of support for `CFA_expression`, which may result in failed stack backtracing in extreme cases.
- When analyzing Lua stacks, the search for the `L` pointer is currently done by assuming it is stored in register `rbx`, which is correct for most cases with `GCC -O2`. However, depending on the optimization level of GCC, the value of `L` may be stored in a different register, leading to failures in Lua stack analysis.
- The analysis of `CFA` instructions does not handle `vdso` at the moment, causing stack backtracing failures for function calls in `vdso`.
- The process of merging C stacks and Lua stacks uses a heuristic strategy, which may have some flaws in extreme cases (none have been found so far).
## Future Work
The following tasks are planned for `lua-perf`:
- Support for `CFA_expression`
- Support for `vdso`
- Dynamic analysis of the `L` register
- Optimization of the merging strategy for C stacks and Lua stacks
- Support for more versions of Lua