#!/usr/bin/bash
# Throttle all CPUs to $1 MHz. Requires cpufreqd and/or cpufrequtils
# (not sure which).
m=${1:-3000}
echo "Try using top speed of ${m}MHz..."
nCpu=$(/usr/bin/lscpu | /usr/bin/awk '/^CPU\(s\):/{print $2}')
if [ x = "x${nCpu}" ]; then
    echo "Cannot determine CPU count" 1>&2
    exit 1
fi
i=0
set -e
while [ $i -lt $nCpu ]; do
    sudo cpufreq-set -c $i -r -d 400MHz -u ${m}MHz
    echo "CPU${i}: ${m}MHz"
    i=$((i + 1))
    # -r "should" set it for all CPUs at once but is not doing so
    # for me.  Indeed, the man page says: On Linux kernels up to
    # 2.6.29, the -r or --related parameter is ignored.
done