Haskell: Benchmark safe foreign call overhead (inspired by https://groups.google.com/forum/#!topic/haskell-cafe/umeWETniZDM)

ffi-overhead.hs

import Criterion.Main
import Foreign.C

foreign import ccall safe   "print" printSafe   :: CInt -> IO ()
foreign import ccall unsafe "print" printUnsafe :: CInt -> IO ()

main = do

  defaultMain
    [ bench "safe"   $ nfIO (printSafe   10)
    , bench "unsafe" $ nfIO (printUnsafe 10)
    ]

Makefile

all:
	ghc -O2 -fforce-recomp ffi-overhead.hs return.c && ./ffi-overhead

output-core-i5.txt

benchmarking safe
mean: 89.20918 ns, std dev: 1.544843 ns

benchmarking unsafe
mean: 7.492741 ns, std dev: 173.1078 ps

return.c

void print(int x){
  return;
}