Add support for Tracy profiler (#15113)

doc/developing/misc.md

@@ -1,6 +1,6 @@
 # Miscellaneous
 
-## Profiling Minetest on Linux
+## Profiling Minetest on Linux with perf
 
 We will be using a tool called "perf", which you can get by installing `perf` or `linux-perf` or `linux-tools-common`.
 
@@ -36,3 +36,54 @@ Give both files to the developer and also provide:
 * commit the source was built from and/or modified source code (if applicable)
 
 Hotspot will resolve symbols correctly when pointing the sysroot option at the collected libs.
+
+
+## Profiling with Tracy
+
+[Tracy](https://github.com/wolfpld/tracy) is
+> A real time, nanosecond resolution, remote telemetry, hybrid frame and sampling
+> profiler for games and other applications.
+
+It allows one to annotate important functions and generate traces, where one can
+see when each individual function call happened, and how long it took.
+
+Tracy can also record when frames, e.g. server step, start and end, and inspect
+frames that took longer than usual. Minetest already contains annotations for
+its frames.
+
+See also [Tracy's official documentation](https://github.com/wolfpld/tracy/releases/latest/download/tracy.pdf).
+
+### Installing
+
+Tracy consists of a client (Minetest) and a server (the gui).
+
+Install the server, e.g. using your package manager.
+
+### Building
+
+Build Minetest with `-DDBUILD_WITH_TRACY=1`, this will fetch Tracy for building
+the Tracy client. And use `FETCH_TRACY_GIT_TAG` to get a version matching your
+Tracy server, e.g. `-DFETCH_TRACY_GIT_TAG=v0.11.0` if it's `0.11.0`.
+
+To actually use Tracy, you also have to enable it with Tracy's build options:
+```
+-DTRACY_ENABLE=1 -DTRACY_ONLY_LOCALHOST=1
+```
+
+See Tracy's documentation for more build options.
+
+### Using in C++
+
+Start the Tracy server and Minetest. You should see Minetest in the menu.
+
+To actually get useful traces, you have to annotate functions with `ZoneScoped`
+macros and recompile. Please refer to Tracy's official documentation.
+
+### Using in Lua
+
+Tracy also supports Lua.
+If built with Tracy, Minetest loads its API in the global `tracy` table.
+See Tracy's official documentation for more information.
+
+Note: The whole Tracy Lua API is accessible to all mods. And we don't check if it
+is or becomes insecure. Run untrusted mods at your own risk.