Disable / Enable HyperThreading cores on runtime - linux

toggleHT.sh

#!/bin/bash

HYPERTHREADING=1

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

function enabled() {
        echo -en "Enabling HyperThreading\n"
        HYPERTHREADING=1
        toggleHyperThreading
}

function disabled() {
        echo -en "Disabling HyperThreading\n"
        HYPERTHREADING=0
        toggleHyperThreading
}

#
ONLINE=$(cat /sys/devices/system/cpu/online)
OFFLINE=$(cat /sys/devices/system/cpu/offline)
echo "---------------------------------------------------"
echo -en "CPU's online: $ONLINE\t CPU's offline: $OFFLINE\n"
echo "---------------------------------------------------"
while true; do
    read -p "Type in e to enable or d disable hyperThreading or q to quit [e/d/q] ?" ed
    case $ed in
        [Ee]* ) enabled; break;;
        [Dd]* ) disabled;exit;;
        [Qq]* ) exit;;
        * ) echo "Please answer e for enable or d for disable hyperThreading.";;
    esac
done