LED CPU Trigger

modulename: ledtrig-cpu.ko

configname: CONFIG_LEDS_TRIGGER_CPU

Linux Kernel Configuration
└─>Device Drivers
└─>LED Support
└─>LED Trigger support
└─>LED CPU Trigger
In linux kernel since version 3.1 (release Date: 2011-10-24)  
This allows LEDs to be controlled by active CPUs. This shows
the active CPUs across an array of LEDs so you can see which
CPUs are active on the system at any given moment.

If unsure, say N.

source code: