Benchmarking GHC

Simon Peyton-Jones simonpj at
Thu Oct 19 10:40:54 EDT 2006

These days -O2, which invokes the SpecConstr pass, can have a big
effect, but only on some programs.


| -----Original Message-----
| From: glasgow-haskell-users-bounces at
[mailto:glasgow-haskell-users-bounces at]
| On Behalf Of Neil Mitchell
| Sent: 19 October 2006 11:22
| To: Donald Bruce Stewart
| Cc: GHC Users Mailing List
| Subject: Re: Benchmarking GHC
| Hi
| > > One thing that IME makes a difference is -funbox-strict-fields.
| > > probably better to use pragmas for this, though.  Another thing to
| > > consider is garbage collection RTS flags, those can sometimes make
| > > big difference.
| >
| I _don't_ want to speed up a particular program by modifying it, I
| want to take a set of existing programs which are treated as black
| boxes, and compile them all with the same flags. I don't want to
| experiment to see which flags give the best particular result on a per
| program basis, or even for the benchmark as a whole, I just want to
| know what the "standard recommendation" is for people who want fast
| code but not to understand anything.
| > All this and more on the under-publicised Performance wiki,
| >
| It's a very good resource, and I've read it before :)
| Another way to treat my question is, the wiki says "Of course, if a
| GHC compiled program runs slower than the same program compiled with
| another Haskell compiler, then it's definitely a bug" - in this
| sentance what does the command line look like in the GHC compiled
| case?
| Thanks
| Neil
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