parallel-dd

#!/bin/bash
trap 'killall -9 parallel-dd' INT

# number of bytes per file
SIZE=12K

# number of threads
THREADS=100

# number of files per thread
FILES_PER_THREAD=300000

TMPDIR=$1

usage="USAGE: parallel-dd TMPDIR\n"

[ -z $TMPDIR ] && printf "$usage" && exit

mkdir -p $TMPDIR

for i in 0 1 2 3 4 5 6 7 8 9 a b c d e f
do
    for j in 0 1 2 3 4 5 6 7 8 9 a b c d e f
    do
	for k in 0 1 2 3 4 5 6 7 8 9 a b c d e f
	do
	    for l in 0 1 2 3 4 5 6 7 8 9 a b c d e f
	    do
		mkdir -p $TMPDIR/$i$j/$k$l
	    done
	done
    done
done


serial_dd() {
    local thread=$1
    mkdir -p ${TMPDIR}/$thread
    # create 300000 files per thread (hence total of 30 million files)
    for count in $(seq 1 ${FILES_PER_THREAD})
    do
        local uuidfile=`uuidgen`
        local part1=`expr substr $uuidfile 1 2`
        local part2=`expr substr $uuidfile 3 2`
        echo $((time (dd if=/dev/zero of=${TMPDIR}/$part1/$part2/$uuidfile bs=${SIZE} count=1 oflag=direct ) 2>&1 ) | grep real | sed -e 's/real//' | tr -d '\t')
    done
}
parallel_dd() {
    for i in $(seq 1 ${THREADS})
    do
        serial_dd $i &
        pids[${i}]=$!
    done
    for pid in ${pids[*]}; do
        wait $pid
    done
    echo -n "Total time: "
}
time parallel_dd 2>&1