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Disable efficiency cores #190

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Merged
merged 5 commits into from
Jul 30, 2025
Merged

Disable efficiency cores #190

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530ca68
Store disabled CPUs
vmcj Jul 30, 2025
8ce7ab7
Store the isolated cores for ansible
vmcj Jul 30, 2025
f95bb4c
Clarify the package/socket usage
vmcj Jul 30, 2025
658a63e
Consider ARM processors
vmcj Jul 29, 2025
1eb5b51
Disable efficiency cores
vmcj Jul 29, 2025
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53 changes: 45 additions & 8 deletions provision-contest/disable-turboboost_ht
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,23 @@ set -eu -o pipefail
shopt -s extglob

declare -A core_ids
declare -a disabled_cores

disable_cpu () {
cpu="$1"
echo 0 > $cpu/online
disabled_cores+=("${cpu##*/}")
}

store_isolcpus_fact="/var/tmp/isolcpus"

# Learn all efficency cores if they exist
cpu_list=()
if [ -f /sys/devices/cpu_atom/cpus ]; then
range="$(cat /sys/devices/cpu_atom/cpus)"
IFS='-' read -r start end <<< "$range"
cpu_list=($(eval echo {$start..$end}))
fi

# shellcheck disable=SC2012
for cpu in $(ls -1d /sys/devices/system/cpu/cpu* | sort --version-sort) ; do
Expand Down Expand Up @@ -32,23 +49,44 @@ for cpu in $(ls -1d /sys/devices/system/cpu/cpu* | sort --version-sort) ; do
chmod a-w $cpu/cpufreq/scaling_{max,min}_freq
fi

# Disable all but one thread on each core. Both core_id and physical_package_id are
# numbers it must be ensured that for the following examples are seen as distinct:
# Disable all but one thread on each core per socket. Both core_id and physical_package_id
# are numbers so it must be ensured that for the following examples are seen as distinct:
# - core_id=1, physical_package=11
# - core_id=11, physycal_package=1
# - core_id=11, physical_package=1
# Simple concatenation would result in the string '111' for both cores. Though `cat`
# adds a newline after each file, we do not want to rely on `cat` to always add this
# 'delimiter'.
core_id=$(cat $cpu/topology/core_id | tr -d '\n')'-'$(cat $cpu/topology/physical_package_id | tr -d '\n')

# Disable all efficiency cores
found=0
for efficiency_core in "${cpu_list[@]}"; do
if [[ "$cpu" == "/sys/devices/system/cpu/cpu$efficiency_core" ]]; then
disable_cpu $cpu
found=1
break
fi
done
if [ "$found" -eq "1" ]; then
continue
fi

if [[ ${core_ids[$core_id]:-} ]]; then
echo 0 > $cpu/online
disable_cpu $cpu
else
core_ids[$core_id]=1
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
# Same for some ARM CPUs
FILE_AMD=$DIR_AMD/boost
if [ -d $DIR_INTEL ]; then
# now disable turbo boost
FILE=$DIR_INTEL/no_turbo
Expand All @@ -61,11 +99,10 @@ if [ -d $DIR_INTEL ]; then
# increase freq from powersaving to normal, but don't overclock
echo 100 > $DIR_INTEL/min_perf_pct
echo 100 > $DIR_INTEL/max_perf_pct
elif [ -d $DIR_AMD ]; then
elif [ -f $FILE_AMD ]; then
# now disable boosting
FILE=$DIR_AMD/boost
echo -n 0 > $FILE || echo "Could not write to '$FILE', ignoring for now..."
if [ $(cat $FILE) -ne 0 ]; then
echo -n 0 > $FILE_AMD || echo "Could not write to '$FILE_AMD', ignoring for now..."
if [ $(cat $FILE_AMD) -ne 0 ]; then
echo "Error: turboboost still enabled!"
exit 1
fi
Expand Down