bench in parallel subshelles two builds of stockfish

bench_parallel.sh

#!/bin/bash
_bench () {
${1} << EOF > /dev/null 2>> ${2}
bench 16 1 ${depth} default depth
EOF
}
# the _bench function customization example
# setoption name SyzygyPath value C:\tablebases\wdl345;C:\tablebases\dtz345
# bench 128 4 ${depth} default depth

if [[ ${#} -ne 4 ]]; then
cat << EOF
usage: ${0} base test depth n_runs
fast test:
${0} ./stockfish_base ./stockfish_test 13 10
slow test:
${0} ./stockfish_base ./stockfish_test 20 10
EOF
exit 1
fi

base=${1}
test=${2}
depth=${3}
n_runs=${4}

# preload of CPU/cache/memory
(_bench ${base} base000.txt)&
(_bench ${test} test000.txt)&
wait

# temporary files initialization
cat /dev/null > base000.txt
cat /dev/null > test000.txt
cat /dev/null > tmp000.txt

# bench loop: SMP bench with background subshells
for ((k=1; k<=${n_runs}; k++)); do
    printf "run %3d /%3d\n" ${k} ${n_runs}

    # swap the execution order to avoid bias
    if [ $((k%2)) -eq 0 ]; then
        (_bench ${base} base000.txt)&
        (_bench ${test} test000.txt)&
        wait
    else
        (_bench ${test} test000.txt)&
        (_bench ${base} base000.txt)&
        wait
    fi
  done

# text processing to extract nps values
cat base000.txt | grep second | grep -Eo '[0-9]{1,}' > base001.txt
cat test000.txt | grep second | grep -Eo '[0-9]{1,}' > test001.txt

for ((k=1; k<=${n_runs}; k++)); do
    echo ${k} >> tmp000.txt
done

printf "\nrun\tbase\ttest\tdiff\n"
paste tmp000.txt base001.txt test001.txt | awk '{printf "%3d  %d  %d  %+d\n", $1, $2, $3, $3-$2}'
paste base001.txt test001.txt | awk '{printf "%d\t%d\t%d\n", $1, $2, $2-$1}' > tmp000.txt

# compute: sample mean, 1.96 * std of sample mean (95% of samples), speedup
# std of sample mean = sqrt(NR/(NR-1)) * (std population) / sqrt(NR)
cat tmp000.txt | awk '{sum1 += $1 ; sumq1 += $1**2 ;sum2 += $2 ; sumq2 += $2**2 ;sum3 += $3 ; sumq3 += $3**2 } END {printf "\nbase = %10d +/- %d\ntest = %10d +/- %d\ndiff = %10d +/- %d\nspeedup = %.6f\n\n", sum1/NR , 1.96 * sqrt(sumq1/NR - (sum1/NR)**2)/sqrt(NR-1) , sum2/NR , 1.96 * sqrt(sumq2/NR - (sum2/NR)**2)/sqrt(NR-1) , sum3/NR  , 1.96 * sqrt(sumq3/NR - (sum3/NR)**2)/sqrt(NR-1) , (sum2 - sum1)/sum1 }'

# remove temporary files
rm -f base000.txt test000.txt tmp000.txt base001.txt test001.txt