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)
if [[ $EUID -ne 0 ]]; then
   echo "This script must be run as root"
   exit 1
fi
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

hey this actually works, nice!

Works like a charm on my old Slackare 14.2 with a i7-4810mq - Thanks!

@samueljon Would it be possibel for you to add a few checks?

1. Check if CPU is HT capable
2. Check if HT is enabled or disabled
3. Check for availabe cores and threads per cores

Edit: Did some work here...
https://gist.github.com/rorar/cebde935cf4dfa6389df96c4df79ce38
Not perfect, still need polishing (colored text output, disable selected cores,...) . Do you want to give it a try?

@samueljon Would it be possibel for you to add a few checks?

1. Check if CPU is HT capable
2. Check if HT is enabled or disabled
3. Check for availabe cores and threads per cores

Edit: Did some work here... https://gist.github.com/rorar/cebde935cf4dfa6389df96c4df79ce38 Not perfect, still need polishing (colored text output, disable selected cores,...) . Do you want to give it a try?

Nice I will have a look when I can @rorar . Thanks for the inspiration in your implementation.