cachecontroller

A Linux kernel module to dynamically disable/enable CPU caches per core via sysfs.

Usage

The module creates /sys/kernel/cache_disable/cpuX/cache_disable for each CPU X.

• Disable Cache for CPU X:

  echo 1 | sudo tee /sys/kernel/cache_disable/cpuX/cache_disable

• Enable Cache for CPU X:

  echo 0 | sudo tee /sys/kernel/cache_disable/cpuX/cache_disable

• Disable Cache for All CPUs:

  for cpu in $(seq 0 $(($(nproc) - 1))); do 
      echo 1 | sudo tee "/sys/kernel/cache_disable/cpu${cpu}/cache_disable"
  done

Mechanism

Disabling sets the CD (Cache Disable) bit and clears the NW (Not Write-through) bit in the CR0 control register, then executes wbinvd to invalidate caches. Re-enabling clears these bits.

Build & Load

1. Build: make (Requires kernel headers)
2. Load: sudo insmod cachecontroller.ko
3. Unload: sudo rmmod cachecontroller