exp-drd/scripts/measurement-functions

#!/bin/bash

########################
# Function definitions #
########################

## Print the logarithm base 2 of $1 on stdout.
function log2 {
  local i

  for ((i=0;i<64;i++))
  do
    if [ $((2**i)) = $1 ]; then
      echo $i
      return 0
    fi
  done
  echo error
  return 1
}

## Print the size of the level 2 cache in bytes on stdout.
function get_cache_size {
  local s
  s=$(</sys/devices/system/cpu/cpu0/cache/index2/size)
  if [ "${s%M}" != "$s" ]; then
    echo $((${s%M}*1024*1024))
  elif [ "${s%K}" != "$s" ]; then
    echo $((${s%K}*1024))
  else
    echo $s
  fi
}

## Read a stream of numbers from stdin (one per line), and print the average
#  and standard deviation.
function avgstddev {
  awk '{n++;sum+=$1;sumsq+=$1*$1}END{d=sumsq/n-sum*sum/n/n;print sum/n,(d>0?sqrt(d):0)}'
}

## Echo all arguments on stderr, run the command passed in $1 .. ${$#} three
#  times, pass the file specified in ${test_input} to the command, write the
#  command output to the file specified in ${test_output}, and print the
#  runtime of the command on stdout.
function measure_runtime {
  echo "$@" >&2
  for ((i=0;i<3;i++))
  do
    cat "${test_input:-/dev/null}" | \
      /usr/bin/time --format="%e" "$@" 2>&1 | \
      tee "${test_output:-/dev/null}" | \
      tail -n 1
  done
}

## Print the average runtime of the command passed in $1 .. ${$#} and the ratio
#  of the runtime to ${avg1} +/- ${stddev1}.
function print_runtime_ratio {
  local tmp

  tmp="/tmp/test-timing.$$"
  rm -f "${tmp}"

  measure_runtime "$@" | avgstddev > "$tmp"
  read avg2 stddev2 < "$tmp"
  echo "Average time: ${avg2} +/- ${stddev2} seconds"
  awk "END{print "'"'"Ratio ="'"'", ${avg2}/${avg1}, "'"'"+/-"'"'", ${avg2}/${avg1}*(${stddev1}/${avg1}+${stddev2}/${avg2})}" </dev/null
}