I recently did the classic "push a shopping cart down the aisle at Fry's" to build a Core 2 Quad computer, with Linux swap and a soft raid array spread across three 750 GB sata hard disks. I had some potential "first build" issues, notably a mishap with the lawn of copper grass that passes for a 775 cpu socket, followed by an hour of brain-surgery with a magnifying glass and a tiny screwdriver. I was very curious to test the stability of this system when it booted up after all; the best hardware test I could think of was multiple processes building GHC from source, with each iteration using the previous GHC binary as the compiler for the new build. Four iterating GHC builds in parallel is enough to peg all four cores at 100% indefinitely, with considerable disk activity to the soft raid array. The most I had going at once was 30 GHC builds; the system remained responsive enough for me to gracefully change my mind in the morning. Building multiple copies of GHC generates a lot of heat; going full tilt, the computer was drawing 220 watts at the wall. I don't use air conditioning for my summer office, so I ended up taping a small bathroom exhaust fan and dimmer switch into the back of a cardboard box, to collect the hot air from the back of the computer and send it out the window through a dryer hose. This kept the cores at 40 C (the enclosure itself has all possible fans) and my office cooler. A previous passive dryer hose arrangement kept the computer at 50 C, which is cooler than my MacBook cpu at full tilt, but I like to build things. Cardboard is an awesome quick prototyping material. Someone else in the same boat might save some time by modifying my Bash script. I ran hundreds of GHC builds without a mishap, and concluded that my system is stable.

#!/bin/bash

# ghc-test.sh

# Bash script to iteratively build ghc from source # http://www.haskell.org/ghc

# usage: # ghc-test iters [ghc]

# Bash scripting reference: Advanced Bash-Scripting Guide # http://tldp.org/LDP/abs/html/index.html

# Customize these parameters to local installation:

sourcedir="/home/me/ghc-6.6.1" src1="${sourcedir}/ghc-6.6.1-src.tar.bz2" src2="${sourcedir}/ghc-6.6.1-src-extralibs.tar.bz2"

testdir="/media/raid/ghc-test" log="${testdir}/log.txt" ghcdir="ghc-6.6.1" binarypath="driver/ghc/ghc"

# determine build directory time=$(date +'%Y%m%d-%H%M%S') builddir="${testdir}/${time}"

# determine number of iterations if [[ -z "$1" ]] then iters=2 else iters=$1 fi

# choose ghc binary to use if [[ -n "$2" && -f $2 && -x $2 ]] then ghc=$2 else ghc=$(which ghc) fi

# check ghc binary for pulse fib=`${ghc} -e 'let x = 0 : 1 : zipWith (+) x (tail x) in x !! 99'` if [[ ${fib} != "218922995834555169026" ]] then echo "** bad ** ${ghc} ${iters} ${time}" >> ${log} ghc=$(which ghc) else echo "ok ${ghc} ${iters} ${time}" >> ${log} fi

# do an iteration if $iters > 0 let iters=iters-1 if [[ ${iters} -gt 0 ]] then

# build new copy of ghc from source mkdir -p ${builddir} cd ${builddir} tar -jxf ${src1} tar -jxf ${src2} cd ${ghcdir} ./configure --with-ghc=${ghc} make

# delete previous build directory, now that we're done with $ghc if [[ -n "$3" && -d "$3" ]] then rm -rf $3 fi

# iterate newghc="${builddir}/${ghcdir}/${binarypath}" ${sourcedir}/ghc-test.sh ${iters} ${newghc} ${builddir}

else

# delete previous build directory if [[ -n "$3" && -d "$3" ]] then rm -rf $3 fi

fi