并行haskell(ghc 6.10.4)不接受-N大于-N1

我正在尝试在OSX10.5上运行GHC6.10.4(来自MacPorts)中的并行代码

我在makefile中使用-threaded构建:

GHC=ghc -prof -auto-all -O -threaded

glicko: glicko.hs Lib.hs
        $(GHC) --make -main-is Glicko glicko.hs lib.hs

./glicko +RTS -N 或 ./glicko +RTS -N1 代码运行,但似乎只使用一个CPU。如果我以 ./glicko +RTS -N2 ,然后我得到了运行时帮助消息,该消息记录了命令行参数;但是文档建议应该运行该程序。

为什么-N2不起作用?

更多时间信息:

$ ./glicko +RTS --info
 [("GHC RTS", "YES")
 ,("GHC version", "6.10.4")
 ,("RTS way", "rts_thr_p")
 ,("Host platform", "i386-apple-darwin")
 ,("Host architecture", "i386")
 ,("Host OS", "darwin")
 ,("Host vendor", "apple")
 ,("Build platform", "i386-apple-darwin")
 ,("Build architecture", "i386")
 ,("Build OS", "darwin")
 ,("Build vendor", "apple")
 ,("Target platform", "i386-apple-darwin")
 ,("Target architecture", "i386")
 ,("Target OS", "darwin")
 ,("Target vendor", "apple")
 ,("Word size", "32")
 ,("Compiler unregisterised", "NO")
 ,("Tables next to code", "YES")
 ]