Multithreading Schmultithreading

Given how a lot of recent vulnerabilities have to do with symmetric multithreading, the world would be a lot safer if all your systems only used a single core:

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for I in /sys/devices/system/cpu/cpu[1-9]*
do
  echo 0 > ${I}/online
done

What it does

It disables every single core but the first one, cpu0.

Why it works

The Linux kernel allows you to enable/disable cores on demand using files under /sys/devices/system/cpu.

TL;DR

• Performance
• Some twisted kind of mitigation for Intel® bugs.
• Fun