microbenchmark – Make Me Engineer

Getting an accurate execution time in C++ (micro seconds)

November 10, 2022 by Tarik

If you are using c++11 or later you could use std::chrono::high_resolution_clock. A simple use case : auto start = std::chrono::high_resolution_clock::now(); … auto elapsed = std::chrono::high_resolution_clock::now() – start; long long microseconds = std::chrono::duration_cast<std::chrono::microseconds>( elapsed).count(); This solution has the advantage of being portable. Beware that micro-benchmarking is hard. It’s very easy to measure the wrong thing (like … Read more

Why does adding an xorps instruction make this function using cvtsi2ss and addss ~5x faster?

July 12, 2022 by Tarik

What is microbenchmarking?

May 21, 2022 by Tarik

It means exactly what it says on the tin can – it’s measuring the performance of something “small”, like a system call to the kernel of an operating system. The danger is that people may use whatever results they obtain from microbenchmarking to dictate optimizations. And as we all know: We should forget about small … Read more

Idiomatic way of performance evaluation?

April 27, 2022 by Tarik

Generally: For repeated short things, you can just time the whole repeat loop. (But microbenchmarking is hard; easy to distort results unless you understand the implications of doing that; for very short things, throughput and latency are different, so measure both separately by making one iteration use the result of the previous or not. Also … Read more

How do I write a correct micro-benchmark in Java?

April 12, 2022 by Tarik

Tips about writing micro benchmarks from the creators of Java HotSpot: Rule 0: Read a reputable paper on JVMs and micro-benchmarking. A good one is Brian Goetz, 2005. Do not expect too much from micro-benchmarks; they measure only a limited range of JVM performance characteristics. Rule 1: Always include a warmup phase which runs your … Read more