Hi Johannes,

see also this wiki page: https://ghc.haskell.org/trac/ghc/wiki/Performance/Runtime.

It mentions the `gcd` regression that you found (and has some analysis), but not the others (`tak` and `exp3_8`). Maybe you could start with updating that page.

Thomas

On Thu, Jan 7, 2016 at 9:55 AM, Simon Peyton Jones <simonpj@microsoft.com> wrote:

Yes we’d love help with investigating, characterising, and fixing performance bugs.

Simon

From: Haskell-Cafe [mailto:haskell-cafe-bounces@haskell.org] On Behalf Of Thomas Miedema
Sent: 07 January 2016 00:52
To: Johannes Waldmann <johannes.waldmann@htwk-leipzig.de>
Cc: Joachim Breitner <mail@joachim-breitner.de>; Haskell cafe <haskell-cafe@haskell.org>
Subject: Re: [Haskell-cafe] long-range performance comparisons (GHC over the years)

I recently noticed a performance problem

...

What worries me is that such a regression
had been sitting there for over a year

There are 215 open runtime performance tickets (out of a total of 1655 open tickets, that makes 13%).

Compared to say new typesystem features, they don't get much attention. Only a few were fixed this year, most of them by Joachim Breitner (the new performance tsar?). He also created https://perf.haskell.org/ghc.

In case you want to help out, start here: https://ghc.haskell.org/trac/ghc/wiki/Newcomers.