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90 lines
3.0 KiB
Markdown
90 lines
3.0 KiB
Markdown
# Profiling
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## Profiling Luanti on Linux with perf
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We will be using a tool called "perf", which you can get by installing `perf` or `linux-perf` or `linux-tools-common`.
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To get usable results you need to build Luanti with debug symbols
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(`-DCMAKE_BUILD_TYPE=RelWithDebInfo` or `-DCMAKE_BUILD_TYPE=Debug`).
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Run the client (or server) like this and do whatever you wanted to test:
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```bash
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perf record -z --call-graph dwarf -- ./bin/luanti
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```
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This will leave a file called "perf.data".
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You can open this file with perf built-in tools but much more interesting
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is the visualization using a GUI tool: **[Hotspot](https://github.com/KDAB/hotspot)**.
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It will give you flamegraphs, per-thread, per-function views and much more.
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### Remote Profiling
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Attach perf to your running server, press *^C* to stop:
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```bash
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perf record -z --call-graph dwarf -F 400 -p "$(pidof minetestserver)"
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```
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Collect a copy of the required libraries/executables:
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```bash
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perf buildid-list | grep -Eo '/[^ ]+(minetestserver|\.so)[^ ]*$' | \
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tar -cvahf debug.tgz --files-from=- --ignore-failed-read
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```
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Give both files to the developer and also provide:
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* Linux distribution and version
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* commit the source was built from and/or modified source code (if applicable)
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Hotspot will resolve symbols correctly when pointing the sysroot option at the collected libs.
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## Profiling with Tracy
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[Tracy](https://github.com/wolfpld/tracy) is
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> A real time, nanosecond resolution, remote telemetry, hybrid frame and sampling
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> profiler for games and other applications.
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It allows one to annotate important functions and generate traces, where one can
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see when each individual function call happened, and how long it took.
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Tracy can also record when frames, e.g. server step, start and end, and inspect
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frames that took longer than usual. Luanti already contains annotations for
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its frames.
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See also [Tracy's official documentation](https://github.com/wolfpld/tracy/releases/latest/download/tracy.pdf).
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### Installing
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Tracy consists of a client (Luanti) and a server (the gui).
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Install the server, e.g. using your package manager.
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### Building
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Build Luanti with `-DDBUILD_WITH_TRACY=1`, this will fetch Tracy for building
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the Tracy client. And use `FETCH_TRACY_GIT_TAG` to get a version matching your
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Tracy server, e.g. `-DFETCH_TRACY_GIT_TAG=v0.11.0` if it's `0.11.0`.
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To actually use Tracy, you also have to enable it with Tracy's build options:
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```
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-DTRACY_ENABLE=1 -DTRACY_ONLY_LOCALHOST=1
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```
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See Tracy's documentation for more build options.
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### Using in C++
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Start the Tracy server and Luanti. You should see Luanti in the menu.
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To actually get useful traces, you have to annotate functions with `ZoneScoped`
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macros and recompile. Please refer to Tracy's official documentation.
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### Using in Lua
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Tracy also supports Lua.
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If built with Tracy, Luanti loads its API in the global `tracy` table.
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See Tracy's official documentation for more information.
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Note: The whole Tracy Lua API is accessible to all mods. And we don't check if it
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is or becomes insecure. Run untrusted mods at your own risk.
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