Disable/enable hyperthreading

set_hyperthreading.sh

#!/bin/bash

hyperthreading=$1

if [[ -z $hyperthreading ]]; then
    echo "Missing argument: Specify 0 to disable hyperthreading and 1 to enable hyperthreading"
    exit 2
fi

# Be careful to not skip the space at the beginning nor the end
CPUS_TO_SKIP=" $(cat /sys/devices/system/cpu/cpu*/topology/thread_siblings_list | sed 's/[^0-9].*//' | sort | uniq | tr "\r\n" "  ") "


for CPU_PATH in /sys/devices/system/cpu/cpu[0-9]*; do
    CPU="$(echo $CPU_PATH | tr -cd "0-9")"
    echo "$CPUS_TO_SKIP" | grep " $CPU " > /dev/null
    if [ $? -ne 0 ]; then
        echo "$hyperthreading > $CPU_PATH/online"
        echo -n $hyperthreading > $CPU_PATH/online
    fi
done