We learn to debug with perf - as many as 18 pages about the main subcommands, features and device tool. Julia recommends; “I even used it several times to profile Ruby programs!”
The difficulty level is for the super-advanced administrator.
When you need to find the cause of the failure without having access to the source codes. All logs have already been viewed, all debug and verbose keys are enabled, and the cause of the problems has not been found - use perf. Required coding skills in languages like C.