Strange performance effects with unsafePerformIO

Björn Peemöller bjp at
Thu Apr 7 14:51:30 CEST 2011

Simon Marlow schrieb:

> Incidentally this will be faster with GHC 7.2, because we implemented
> chunked stacks, so unsafePerformIO never has to traverse more than 32k
> of stack (you can tweak the chunk size with an RTS option).  This is
> still quite a lot of overhead, but at least it is bounded.
> The example above runs in 1.45s for me with current HEAD, and I gave up
> waiting with 7.0.

Thank you all for your explanations,

the blackholing indeed seems to be the cause for the slowdown. Is there
any documentation available about the blackholing process?

Maybe we can find a hint on how to change our code to avoid the problem.


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