| #!/bin/bash -e |
| # |
| # Licensed to the Apache Software Foundation (ASF) under one |
| # or more contributor license agreements. See the NOTICE file |
| # distributed with this work for additional information |
| # regarding copyright ownership. The ASF licenses this file |
| # to you under the Apache License, Version 2.0 (the |
| # "License"); you may not use this file except in compliance |
| # with the License. You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, |
| # software distributed under the License is distributed on an |
| # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| # KIND, either express or implied. See the License for the |
| # specific language governing permissions and limitations |
| # under the License. |
| |
| # Ensure that the CPU governor is set to a particular governor, outputting |
| # the prior governor on stdout. |
| # |
| # Without this, some of our tests end up having higher variance due to |
| # changing CPU speed during the test. |
| # |
| # Assumes that all CPUs are set to the same governor. |
| target_governor=$1 |
| old_governor=$(cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor) |
| for cpu_dir in /sys/devices/system/cpu/cpu[0-9]*/ ; do |
| governor_file=$cpu_dir/cpufreq/scaling_governor |
| governor=$(cat $governor_file) |
| if [ "$governor" != "$target_governor" ]; then |
| >&2 echo "CPU $cpu_dir not in '$target_governor' mode. Attempting to change" |
| echo $target_governor | sudo tee $governor_file > /dev/null |
| if [ $? -ne 0 ]; then |
| >&2 echo Could not set $target_governor governor! |
| >&2 echo Perhaps you need passwordless sudo for this user |
| exit 1 |
| fi |
| fi |
| done |
| echo $old_governor |
