devilutionX/docs/profiling-linux.md

Profiling on Linux

If you're trying to make DevilutionX run faster or use less memory, profiling can be very helpful.

gperftools

gperftools is a library that provides a heap profiler and a CPU profiler.

To install gperftools on Debian and Ubuntu, simply run:

sudo apt install libgoogle-perftools-dev

You may also want to install debugging symbols for SDL2:

sudo apt install libsdl2-dev-dbgsym

gperftools by default only comes with a basic visualizer. pprof, also from Google, is a more fully-featured profile visualizer that provides an interactive web server with a flame graph, source annotation, etc.

To install pprof, run:

go install github.com/google/pprof@latest

CPU profiling with gperftools

cmake -S. -Bbuild-gperf -DCMAKE_BUILD_TYPE=RelWithDebInfo -DGPERF=ON -DBUILD_TESTING=ON

Timedemo:

tools/build_and_run_benchmark.py --gperf devilutionx -- --diablo --spawn --lang en --demo 0 --timedemo

Individual benchmarks (built when BUILD_TESTING is ON):

tools/build_and_run_benchmark.py --gperf clx_render_benchmark

Heap profiling with gperftools

Heap profiling produces a graph of all heap allocations that are alive between two points in a program.

DevilutionX has built-in support for heap allocation via gperftools.

Then, configure and build DevilutionX with the GPERF option:

cmake -S. -Bbuild-gperf -DCMAKE_BUILD_TYPE=RelWithDebInfo -DGPERF=ON -DGPERF_HEAP_FIRST_GAME_ITERATION=ON
cmake --build build-gperf -j $(nproc)

The GPERF_HEAP_FIRST_GAME_ITERATION option will make DevilutionX dump the heap profile of the first game iteration.

Start DevilutionX and load a game:

build-gperf/devilutionx

Heap profile data will be generated at main.0001.heap.

To inspect the profile, run:

google-pprof --web build-gperf/devilutionx main.0001.heap

See gperftools heap profiling documentation for more information.