Copyright © Red Hat, Inc.
By default, Container Linux uses the "performance" CPU governor meaning that the CPU operates at the maximum frequency regardless of load. This is reasonable for a system that is under constant load or cannot tolerate increased latency. On the other hand, if the system is idle much of the time and latency is not a concern, power savings may be desired.
Several governors are available:
| Governor | Description |
|---|---|
performance |
Default. Operate at the maximum frequency |
ondemand |
Dynamically scale frequency at 75% cpu load |
conservative |
Dynamically scale frequency at 95% cpu load |
powersave |
Operate at the minimum frequency |
userspace |
Controlled by a userspace application via the scaling_setspeed file |
The "conservative" governor can be used instead using the following shell commands:
modprobe cpufreq_conservative
echo "conservative" | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor > /dev/null
This can be configured with a Container Linux Config as well:
# This config is meant to be consumed by the config transpiler, which will
# generate the corresponding Ignition config. Do not pass this config directly
# to instances of Container Linux.
systemd:
units:
- name: cpu-governor.service
enable: true
contents: |
[Unit]
Description=Enable CPU power saving
[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/usr/sbin/modprobe cpufreq_conservative
ExecStart=/usr/bin/sh -c '/usr/bin/echo "conservative" | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor'
[Install]
WantedBy=multi-user.target
{
"ignition": {
"config": {},
"timeouts": {},
"version": "2.1.0"
},
"networkd": {},
"passwd": {},
"storage": {},
"systemd": {
"units": [
{
"contents": "[Unit]\nDescription=Enable CPU power saving\n\n[Service]\nType=oneshot\nRemainAfterExit=yes\nExecStart=/usr/sbin/modprobe cpufreq_conservative\nExecStart=/usr/bin/sh -c '/usr/bin/echo \"conservative\" | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor'\n\n[Install]\nWantedBy=multi-user.target",
"enable": true,
"name": "cpu-governor.service"
}
]
}
}
More information on further tuning each governor is available in the Kernel Documentation
Copyright © Red Hat, Inc.