On 27/11/12 14:52, Ian Lynagh wrote:
Hi all,
GHC HEAD now has support for using dynamic libraries by default (and in particular, using dynamic libraries and the system linker in GHCi) for a number of platforms.
This has some advantages and some disadvantages, so we need to make a decision about what we want to do in GHC 7.8. There are also some policy questions we need to answer about how Cabal will work with a GHC that uses dynamic libraries by default. We would like to make these as soon as possible, so that GHC 7.6.2 can ship with a Cabal that works correctly.
The various issues are described in a wiki page here: http://hackage.haskell.org/trac/ghc/wiki/DynamicByDefault
Thanks for doing all the experiments and putting this page together, it certainly helps us to make a more informed decision.
If you have a few minutes to read it then we'd be glad to hear your feedback, to help us in making our decisions
My personal opinion is that we should switch to dynamic-by-default on all x86_64 platforms, and OS X x86. The performance penalty for x86/Linux is too high (30%), and there are fewer bugs affecting the linker on that platform than OS X. I am slightly concerned about the GC overhead on x86_64/Linux (8%), but I think the benefits outweigh the penalty there, and I can probably investigate to find out where the overhead is coming from. Cheers, Simon