harfbuzz/perf/README.md

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# Building and Running
Benchmarks are implemented using [Google Benchmark](https://github.com/google/benchmark).
To build the benchmarks in this directory you need to set the benchmark
option while configuring the build with meson:
```
meson configure build -Dbenchmark=enabled --buildtype=release
```
Then build the benchmark binaries with ninja:
```
ninja -Cbuild perf/benchmark-set
```
Finally, to run one of the benchmarks:
```
./build/perf/benchmark-set
```
It's possible to filter the benchmarks being run and customize the output
via flags to the benchmark binary. See the
[Google Benchmark User Guide](https://github.com/google/benchmark/blob/main/docs/user_guide.md#user-guide) for more details.
# Profiling
Configure the build to include debug information for profiling:
```
CXXFLAGS="-fno-omit-frame-pointer" meson --reconfigure build -Dbenchmark=enabled --buildtype=debug
ninja -Cbuild
```
Then run the benchmark with perf:
```
perf record -g -o ~/tmp/profiles/subset.prof ./build/perf/benchmark-subset --benchmark_filter="BM_subset_codepoints/subset_notocjk/100000" --benchmark_repetitions=5
```
You probably want to filter to a specific benchmark of interest and set the number of repititions high enough to get a good sampling of profile data.
Finally view the profile with:
perf report -i ~/tmp/profiles/subset.prof