Disable / Enable HyperThreading cores on runtime - linux

toggleHT.sh

#!/bin/bash
# Turn hyperthreading on or off.

HYPERTHREADING=1
RED="\033[0;31m"
GREEN="\033[0;32m"
YELLOW="\033[0;33m"
ENDCOLOR="\033[0m"

function toggleHyperThreading() {
  for CPU in /sys/devices/system/cpu/cpu[0-9]*; do
      CPUID=`basename ${CPU} | cut -b4-`
      printf "${YELLOW}CPU: ${CPUID}${ENDCOLOR}\t"
      [ -e ${CPU}/online ] && printf "1" > ${CPU}/online
      THREAD1=`cat ${CPU}/topology/thread_siblings_list | cut -f1 -d,`
      if [ ${CPUID} = ${THREAD1} ]; then
          printf "${GREEN}-> enable${ENDCOLOR}\n"
          [ -e ${CPU}/online ] && printf "1" > ${CPU}/online
      else
        if [ "${HYPERTHREADING}" -eq "0" ]; then printf "${YELLOW}-> disabled${ENDCOLOR}\n"; else printf "${GREEN}-> enable${ENDCOLOR}\n"; fi
          printf "${HYPERTHREADING}" > ${CPU}/online
      fi
  done
}

function enabled() {
        printf "${GREEN}Enabling HyperThreading${ENDCOLOR}\n"
        HYPERTHREADING=1
        toggleHyperThreading
}

function disabled() {
        printf "${YELLOW}Disabling HyperThreading${ENDCOLOR}\n"
        HYPERTHREADING=0
        toggleHyperThreading
}

function check_privilege() {
  WHOAMI=$(/usr/bin/whoami)
  if [ "${WHOAMI}" != "root" ] ; then
    printf "${RED}Script must be run with proper user priviledges.${ENDCOLOR}\n"
    exit 1
  fi
}

ONLINE=$(cat /sys/devices/system/cpu/online)
OFFLINE=$(cat /sys/devices/system/cpu/offline)
printf "${YELLOW}%s\n" "---------------------------------------------------"
printf "CPU's online: ${GREEN}${ONLINE}${YELLOW}\t CPU's offline: ${RED}${OFFLINE}\n"
printf "${YELLOW}%s${ENDCOLOR}\n" "---------------------------------------------------"
check_privilege
read -p "Type in e to enable or d disable hyperThreading or q to quit [e/d/q] ?" ed
case ${ed} in
  [Ee]* ) enabled; exit;;
  [Dd]* ) disabled; exit;;
  [Qq]* ) exit;;
  * ) printf "${YELLOW}Please answer e for enable or d for disable hyperThreading.${ENDCOLOR}\n";;
esac