Guidelines for writing Benchmarks for a General Repository.

[GTron-1729]

As per asv documentation it tell us how to write benchmarks, But I want to write benchmarks for say any repo. So, what kind of benchmarks should I write? How do I start? do I need to understand full repo to write any benchmark? Give me a beginner guideline with some sample benchmarks, without me fully understanding the repo? Help would be appreciated.