Parallel/smp Runtime

[humasect]

ghc-6.6: --interactive can't be used with -prof, -ticky, -unreg or -smp.

+RTS -N2 is working fine. But this needs -threaded

[simonmar]

Looks like the error message is misleading; you can indeed use +RTS -N2 with GHCi (althogh I don't think I've ever tried it!).

[humasect]

Yes, I almost thought this would do it, there is no error when executing GHCi this way. But actually:

4.12.1. Options to enable SMP parallelism

In order to make use of multiple CPUs, your program must be linked with the -threaded option (see Section 4.10.7, “Options affecting linking”). Then, to run a program on multiple CPUs, use the RTS -N option <cut>

Would this only mean that GHC needs to be instead built with -threaded +RTS -Nx for this ability? We need the computing power over here.

[simonmar]

Fixed, you can now say 'ghci -threaded'. The -threaded option doesn't actually do anything, because as you say, what matters is what RTS GHCi itself is linked against, and by default it is linked against the threaded RTS.

To merge:

Tue Jan 16 12:04:09 GMT 2007  Simon Marlow <simonmar@microsoft.com>
  * allow 'ghci -threaded' (fixes #1101)

[igloo]

Merged to the 6.6 branch.

[humasect]

Excellent, works great, thank you both!