Benchmarks Game/Parallel/BinaryTrees

Binary Trees

• http://shootout.alioth.debian.org/u64q/benchmark.php?test=binarytrees&lang=ghc&id=1

= Parallel Strategies: parMap

• Status: submitted.

Flags:

   $ ghc -O2 --make -fasm -threaded  Parallel.hs
   $ ./Parallel 20 +RTS -N5 -A350M

{-# OPTIONS -fbang-patterns -funbox-strict-fields #-}
--
-- The Computer Language Shootout
-- http://shootout.alioth.debian.org/
--
-- Contributed by Don Stewart and Thomas Davie
--
-- This implementation uses a parallel strategy to exploit the quad core machine.
-- For more information about Haskell parallel strategies, see,
--
--  http://www.macs.hw.ac.uk/~dsg/gph/papers/html/Strategies/strategies.html
--

import System
import Data.Bits
import Text.Printf
import Control.Parallel.Strategies
import Control.Parallel

--
-- an artificially strict tree.
--
-- normally you would ensure the branches are lazy, but this benchmark
-- requires strict allocation.
--
data Tree = Nil | Node !Int !Tree !Tree

minN = 4

io s n t = printf "%s of depth %d\t check: %d\n" s n t

main = do
    n <- getArgs >>= readIO . head
    let maxN     = max (minN + 2) n
        stretchN = maxN + 1

    -- stretch memory tree
    let c = check (make 0 stretchN)
    io "stretch tree" stretchN c

    -- allocate a long lived tree
    let !long    = make 0 maxN

    -- allocate, walk, and deallocate many bottom-up binary trees
    let vs = (parMap rnf) (depth' maxN) [minN,minN+2..maxN]
    mapM_ (\((m,d,i)) -> io (show m ++ "\t trees") d i) vs

    -- confirm the the long-lived binary tree still exists
    io "long lived tree" maxN (check long)

-- generate many trees
depth' :: Int -> Int -> (Int,Int,Int)
depth' m d =
  (2*n,d,sumT d n 0)
  where
    n = 1 `shiftL` (m - d + minN)

-- allocate and check lots of trees
sumT :: Int -> Int -> Int -> Int
sumT d 0 t = t
sumT  d i t = sumT d (i-1) (t + a + b)
  where a = check (make i    d)
        b = check (make (-i) d)

-- traverse the tree, counting up the nodes
check :: Tree -> Int
check Nil          = 0
check (Node i l r) = i + check l - check r

-- build a tree
make :: Int -> Int -> Tree
make i 0 = Node i Nil Nil
make i d = Node i (make (i2-1) d2) (make i2 d2)
  where i2 = 2*i; d2 = d-1