Great! Thanks for y'all putting effort towards performance. It really is crucial
for developer productivity.

In the particular case of haskell-src-exts, I found that removing many of the
more complicated typeclasses from deriving (Data, Generics, etc) brought the
compilation time way down. IIRC it was pretty drastic, like 40 seconds vs 10
seconds (that could be just the timing for that one types module though, I
don't recall).  Could be valuable to investigate exactly what's going on there.

-Michael

On Tue, Mar 29, 2016 at 2:00 PM, Ömer Sinan Ağacan <omeragacan@gmail.com> wrote:
Hi all,

Using Ben's timing patch [^1], Cabal, and a Haskell program to parse generated
logs [^2], I generated some tables that show compile times of modules in hxt,
haskell-src-exts, lens, and all of their dependencies:

https://gist.githubusercontent.com/osa1/fd82335181a584679c9f3200b7b0a8a5/raw/5d46b0e7006c7ef9fae913f7d6932b74c83835f1/gistfile1.txt

Some notes:

- Modules and passes in modules are sorted.

- At the end of the file you can see the cumulative numbers for the passes. In
  fact, that's a small table so I'm just going to paste it here:

    ======================Total======================
    CodeGen                                    41.32%
    Simplifier                                 34.83%
    Renamer/typechecker                        12.22%
    Desugar                                     2.11%
    CorePrep                                    1.90%
    Demand analysis                             1.44%
    CoreTidy                                    1.35%
    Called arity analysis                       1.10%
    Float inwards                               0.96%
    Common sub-expression                       0.87%
    Parser                                      0.75%
    SpecConstr                                  0.57%
    Specialise                                  0.30%
    Worker Wrapper binds                        0.17%
    Liberate case                               0.12%
    ByteCodeGen                                 0.00%
    Simplify                                    0.00%

I don't know how to make use of this yet, but I thought ghc-devs may find it
useful.

As a next thing I'm hoping to add some more `withTiming` calls. The analyze
program can handle nested `withTiming` calls and renders passes as a tree (GHC
HEAD doesn't have nested `withTiming`s so we don't see it in the file above),
so we can benchmark things in more details. I also want to experiment a little
bit with different `force` parameters to `withTiming`. If anyone has any other
ideas I can also try those.

---

[^1]: https://phabricator.haskell.org/D1959
[^2]: https://github.com/osa1/analyze-ghc-timings
_______________________________________________
ghc-devs mailing list
ghc-devs@haskell.org
http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs