How to Optimize php Performance? And php performance testing ideas?

  question

A php project, or product, is from scratch, from few users to tens of thousands of users, or even more. There are many performance bottlenecks, ranging from rapid project development without paying attention to sql statements to optimization of sql statements. From no cache, to adding cache, cache servers from one to many, etc.

Now, sometimes there will be some confusion, although with continuous optimization, the performance has gradually improved. However, how many percentage points have been raised after optimization, how to detect and how to record are all questions.

Thank you very much.

Xhprof can see that code execution takes time everywhere.
There is also the need to use benchmark tools.
The performance bottleneck is mainly io, with the focus on this