Benchmark Rust code #933
Benchmark Rust code #933
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| let obj = mmtk_dummyvm::object_model::VMObjectModel::address_to_ref(addr); | ||
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| c.bench_function("sft read", |b| { | ||
| b.iter(|| api::mmtk_is_in_mmtk_spaces(black_box(obj))) |
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This test is accessing the SFT entry of the same object again and again. The cache will always hit in this case. I recommend adding a test case where we access the SFT randomly. To make the performance comparison fair and stable, we can use a pseudo random number generator so that we always access the objects in the same "random" order.
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It is possible. We could control what we want to benchmark. criterion provides an approach that allows us to microbenchmark short running functions. It is useful when we can isolate one function and check the performance of the function so that we can make changes to it with more confidence. It is a complement to what we usually do for benchmarking.
Though we can control what we want to benchmark, I am not convinced if we would like to use micro benchmarks to mimic a real situation. Using a larger benchmark or real workload is usually a better option.
Also for this case, I don't think we want to take cache locality into consideration. For SFT access, I would like to measure the performance impact of the code change for #931. Cache locality is not what I am trying to measure, and randomly accessing memory would just add more noise to the result.
This PR allows benchmarking mmtk-core code in DummyVM. It uses
criterion, which is a popular framework to benchmark with a stable Rust toolchain. This PR just introduces code and two benchmarks that specifically test our allocation code in Rust and our SFT read access. This PR does not include those benchmarks in the CI.