# Profiling the compiler

This discussion talks about how profile the compiler and find out
where it spends its time.  If you just want to get a general overview,
it is often a good idea to just add `-Zself-profile` option to the
rustc command line. This will break down time spent into various
categories.  But if you want a more detailed look, you probably want
to break out a custom profiler.


# Profiling the compiler

This section talks about how to profile the compiler and find out where it spends its time.  

Depending on what you're trying to measure, there are several different approaches:

- If you want to see if a PR improves or regresses compiler performance:
  - The [rustc-perf](https://github.com/rust-lang-nursery/rustc-perf) project makes this easy and can be triggered to run on a PR via the `@rustc-perf` bot.
  
- If you want a medium-to-high level overview of where `rustc` is spending its time:
  - The `-Zself-profile` flag and [measureme](https://github.com/rust-lang/measureme) tools offer a query-based approach to profiling.
    See [their docs](https://github.com/rust-lang/measureme/blob/master/summarize/Readme.md) for more information.
    
- If you want function level performance data or even just more details than the above approaches:
  - Consider using a native code profiler such as [perf](profiling/with_perf.html).


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Add mentions and links to `rustc-perf` and `measureme`.