[Haskell-cafe] Compiled program using OpenGL fails to trigger GPU switch on Mac, but works in GHCi

[John Lato]

Hello,

Unfortunately I don't have much to add.

On Wed, Mar 13, 2013 at 9:51 PM, Jesper Särnesjö <sarnesjo at gmail.com> wrote:

> Hi everybody,
>
> This started out on haskell-beginners, as a question about poor
> performance for a Haskell program using OpenGL. Thanks to a few good
> suggestions there, I've managed to figure out more or less what the
> underlying problem is, but not its cause.
>
> In short, I have two programs, one written in Haskell [1] and one
> written in C [2], that consist of calls to the same functions, in the
> same order, to the same C library, but which do not exhibit the same
> behavior. Further, the Haskell program behaves differently when
> compiled using GHC, and when run in GHCi. I would like to know why
> this is, and how to fix it.
>

There are two major differences between compiled code and code run from
ghci.  First, ghci always uses the threaded runtime (compiled with
-threaded).  Second, optimization levels.

If you compile your program with -threaded, do you get the desired behavior
(e.g. does it work the same as with ghci)?

John L.
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