Store the isolated cores for ansible

This is defence in depth by disallowing the kernel to schedule work on the online cpu's before the script disables the CPU's. The script can fail when the CPU taken down is currently working on something.

Author: vmcj

provision-contest/disable-turboboost_ht

@@ -12,6 +12,8 @@ disable_cpu () {
   disabled_cores+=("${cpu##*/}")
 }
 
+store_isolcpus_fact="/var/tmp/isolcpus"
+
 # shellcheck disable=SC2012
 for cpu in $(ls -1d /sys/devices/system/cpu/cpu* | sort --version-sort) ; do
     [[ $(basename $cpu) =~ ^cpu[0-9]+$ ]] || continue
@@ -54,6 +56,11 @@ for cpu in $(ls -1d /sys/devices/system/cpu/cpu* | sort --version-sort) ; do
     fi
 done
 
+if [ -n "${store_isolcpus_fact}" ]; then
+  csv_string=$(IFS=, ; echo "${disabled_cores[*]}")
+  echo "$csv_string" > "$store_isolcpus_fact"
+fi
+
 DIR_INTEL=/sys/devices/system/cpu/intel_pstate
 DIR_AMD=/sys/devices/system/cpu/cpufreq
 if [ -d $DIR_INTEL ]; then