Disk stat watcher

diskstats.sh

#!/bin/bash

# Update interval
INT=0.1

# "Sample count" for speed calculations (for averaging)
SC=20

FROMBOOT=false

#for i in "$@"; do
while [[ $# -gt 0 ]]; do
case "$1" in
  -i|--interval)
    INT="$2"
    echo "INT=${INT}"
    shift
    shift
    ;;
  -s|--samples)
    SC="$2"
    echo "SC=${SC}"
    shift
    shift
    ;;
  -b|--boot)
    # START from boot time
    FROMBOOT=true
    shift
    ;;
  -r|--runtime)
    # RUNTIME only (ie. time span from START to NOW)
    TF="RUN"
    shift
    ;;
  --fulltime)
    # From START to NOW for RUNTIME
    TF="FULL"
    shift
    ;;
  -f|--fromstart)
    # From START for RUNTIME
    TF="FROMSTART"
    shift
    ;;
  *)
    echo "Invalid option: ${i}"
    exit 1
    ;;
esac
done

# Non-breaking space
NBSP="\xC2\xA0"

# "Buffers" for storing disk data
NB=$((SC + 1))
LAST=$((NB - 1))

# Need gawk for big numbers 
AWK="gawk --bignum"

# Sectors (512 bytes) to GiB and MiB
S2G="512 / 1073741824"
S2M="512 / 1048576"

# Nanos in s
NS=1000000000

# awk raw stat print
# Output: device/Total, sectors read, sectors written, time in seconds
PRAW="print \$3, \$6, \$10, now"
PRAWTOT="print \"Total\", tsr, tsw, now"

# awk printf for calculated values
# Input:
#   device, NEWEST sectors read, NEWEST sectors written, NEWEST time in seconds, device, OLDEST sectors read, OLDEST sectors written, OLDEST time in seconds
# Output (+erase to end of line):
#   dev, sectors read, sectors written, GiBs read, GiBs writted, GiBs xferred, read speed, write speed, xfer speed
FMTCALC="%s %d %d %.2f %.2f %.2f %.2f %.2f %.2f\033[0K\n"
PCALC="printf(\"${FMTCALC}\", \$1, \$2, \$3, \
\$2 * ${S2G}, \$3 * ${S2G}, (\$2 + \$3) * ${S2G}, \
(\$2 - \$6) * ${S2M} / dt, (\$3 - \$7) * ${S2M} / dt, ((\$2 - \$6) + (\$3 - \$7)) * ${S2M} / dt)"

# awk relative stats print
# Output: device, sectors read, sectors written, time in seconds
PREL="print \$1, \$2 - \$6, \$3 - \$7, \$4 - \$8"


# Print device, sectors read, sectors written for devices and total
function rawstats {
  cat /proc/diskstats | egrep "sd\w |mmcblk[0-9] |nvme[0-9]n[0-9] " | ${AWK} "{now=$(date +%s%N);tsr+=\$6; tsw+=\$10; ${PRAW}} END {${PRAWTOT}}" | sort -f
}

# Print "zero stats" when starting from system boot time
function zerostats {
  cat /proc/diskstats | egrep "sd\w |mmcblk[0-9] |nvme[0-9]n[0-9] " | ${AWK} "{now=0; \$6=0; \$10=0; ${PRAW}} END {tsr=0; tsw=0; ${PRAWTOT}}" | sort -f
}

# Print device, sectors read, sectors written for devices and total relative to start values
function relstats {
  RAW="$(rawstats)"
  PASTESTATS=("${RAW}" "${SVALS}")
  REL="$(pastestats)"
  echo "${REL}" | ${AWK} "{${PREL}}"
}

# Combine newest and oldest stats
# Output: device, FIRST sectors read, FIRST sectors written, FIRST time in seconds, device, SECOND sectors read, SECOND sectors written, SECOND time in seconds
function pastestats {
  paste <(echo -n "${PASTESTATS[0]}") <(echo "${PASTESTATS[1]}")
}

# Combine newest and oldest stats
# Output: device, NEWEST sectors read, NEWEST sectors written, NEWEST time in seconds, device, OLDEST sectors read, OLDEST sectors written, OLDEST time in seconds
function combinestats {
  # Shift BUF and add new stats, newest data is last
  NEW="$(relstats)"
  BUF=("${BUF[@]:1}" "${NEW}")
  # Combine newest and oldest
  PASTESTATS=("${BUF[SC]}" "${BUF[0]}")
  ALL="$(pastestats)"
}

function calcstats {
  # Headers + erase to end of line
  echo -e "${NBSP} Read Written Read Written Xferred Reading Writing Xferring\033[0K"
  echo -e "${NBSP} sectors sectors GiBs GiBs GiBs MiB/s MiB/s MiB/s\033[0K"
  # awk Cumulative xref speed print
  PREL="printf(\"Cumul.rate ${NBSP} ${NBSP} ${NBSP} ${NBSP} ${NBSP} %.2f %.2f %.2f\033[0K\n\", \$2 * ${S2M} / el, \$3 * ${S2M} / el,  cx / el)"
  NOW="$(date +%s%N)"
  ${AWK} "{dt=(\$4 - \$8) / ${NS};cx=(\$2 + \$3) * ${S2M}; ${PCALC}} END {el=(${NOW} - ${START}) / ${NS};${PREL}}"
}

# Read cursor position to CPOS array where 0=row and 1=col
# See: https://stackoverflow.com/a/51930257
function readcpos {
    local v=() t=$(stty -g)
    stty -echo
    printf "\033[6n"
    IFS='[;' read -ra v -d R
    stty $t
    CPOS=("${v[@]:1}")
}

# Update relative time. Bash won't do floating point so awk ftw.
AWKRELTIME="{
  dt = (\$2 - \$1) / ${NS};
  d = int(dt / 60 / 60 / 24);
  h = int(dt / 60 / 60 % 24);
  m = int(dt / 60 % 60);
  s = int(dt % 60);
  if (d > 0) sd = sprintf(\"%d day%s \", d, d != 1 ? \"s\" : \"\");
  if (h > 0) sh = sprintf(\"%d hour%s \", h, h != 1 ? \"s\" : \"\");
  if (m > 0) sm = sprintf(\"%d minute%s \", m, m != 1 ? \"s\" : \"\");
  if (s > 0 || d + h + m == 0) ss = sprintf(\"%d second%s \", s, s != 1 ? \"s\" : \"\");
  print sd sh sm ss;
}"
function updatereltime {
  NOW="$(date +%s%N)"
  RELTIME="$(${AWK} "${AWKRELTIME}" <<< "${START} ${NOW}")"
}

# Update time string printed at top
function updatetime {
  case "${TF}" in
    RUN)
      updatereltime
      TIMESTR="Stats for last ${RELTIME}"
      ;;
    FULL)
      updatereltime
      TIMESTR="From ${STARTDATE} to $(date +%c) for ${RELTIME}"
      ;;
    FROMSTART)
      updatereltime
      TIMESTR="From ${STARTDATE} for ${RELTIME}"
      shift
      ;;
    *)
      TIMESTR="From ${STARTDATE} to $(date +%c)"
      ;;
  esac
}

# Do the dump
function  dumpstats {
  # Date to top left corner + erase to end of line
  #echo -e "\033[0;0HFrom ${STARTDATE} to $(date)\033[0K"
  updatetime
  echo -e "\033[0;0H${TIMESTR}\033[0K"
  # Dump stats
  echo "${ALL}"| calcstats | column -t -s " "
  # Erase to end of screen.
  # Just to clear any accidental key presses and such.
  echo -en "\033[0J"
}

RUNNING=true

# Trap SIGINT to stop
trap interrupted INT
function interrupted {
  RUNNING=false
}

# Store start time and date and init start values
if [ "${FROMBOOT}" = true ]; then
  BOOTTIME="$(cut -f1 -d' ' /proc/uptime) seconds ago"
  START="$(date -d "${BOOTTIME}" +'%s%N')"
  STARTDATE="$(date -d "${BOOTTIME}" +%c)"
  SVALS="$(zerostats)"
else
  START="$(date +%s%N)"
  STARTDATE="$(date +%c)"
  SVALS="$(rawstats)"
fi

# Init BUF
for i in $(seq 1 $((SC + 1))); do
  BUF=("${BUF[@]}" "$(relstats)")
done

# Clear screen by scrolling old stuff out. This way last dump
# gets printed nicely after any previous commands.
# printf is tricked to repeat n times with seq.
readcpos
printf "\033[1S%.0s" $(seq 2 ${CPOS[0]})

# Hide cursor, use alternate buffer and erase the whole screen
echo -en "\033[?25l\033[?1049h\033[0;0H\033[0J"

# Loop until stopped.
while true; do
  # Put newest and oldest stats together to ALL
  combinestats

  # Dump stats
  dumpstats

  # Exit loop at the end to keep last dump nice and clean.
  sleep ${INT}
  if ! [ "${RUNNING}" = true ]; then break; fi
done

# Back to original buffer and dump stats there too so
# they'll show up nicely in terminal scrollback.
echo -e "\033[?1049l"
dumpstats

# Reset any possible ansi styles and make cursor visible again.
echo -e "\033[0m\033[?25h"