Store the isolated cores for ansible

A bit of defence in depth as this would make that we don't allow the kernel to schedule work before disabling. This should make that the disabling has a lower change of failing.

Author: vmcj

provision-contest/disable-turboboost_ht

@@ -4,6 +4,7 @@ set -eu -o pipefail
 shopt -s extglob
 
 declare -A core_ids
+declare -A disabled_cores
 
 # Learn all efficency cores if they exist
 cpu_list=()
@@ -13,6 +14,14 @@ if [ -f /sys/devices/cpu_atom/cpus ]; then
   cpu_list=($(eval echo {$start..$end}))
 fi
 
+disable_cpu () {
+  cpu="$1"
+  echo 0 > $cpu/online
+  disabled_cores+=("${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
@@ -53,7 +62,7 @@ for cpu in $(ls -1d /sys/devices/system/cpu/cpu* | sort --version-sort) ; do
     found=0
     for efficiency_core in "${cpu_list[@]}"; do
       if [[ "$cpu" == "/sys/devices/system/cpu/cpu$efficiency_core" ]]; then
-        echo 0 > $cpu/online
+        disable_cpu $cpu
         found=1
         break
       fi
@@ -63,7 +72,7 @@ for cpu in $(ls -1d /sys/devices/system/cpu/cpu* | sort --version-sort) ; do
     fi
 
     if [[ ${core_ids[$core_id]:-} ]]; then
-        echo 0 > $cpu/online
+        disable_cpu $cpu
     else
         core_ids[$core_id]=1
     fi
@@ -94,3 +103,8 @@ elif [ -d $DIR_AMD ]; then
 else
     echo "Warning: kernel (turbo) boost config not found in '$DIR_INTEL' or '$DIR_AMD'."
 fi
+
+if [ -n "${store_isolcpus_fact}" ]; then
+  csv_string=$(IFS=, ; echo "${disabled_cores[*]}")
+  echo "$csv_string" > "$store_isolcpus_fact"
+fi