====== cpufreq ======

===== sys interface =====
<code bash>
ls -l /sys/devices/system/cpu/cpu0/cpufreq/
-r--r--r-- 1 root root 4096 lis 14 12:18 affected_cpus             0
-r--r--r-- 1 root root 4096 lis 14 13:08 bios_limit                3400000
-rw-r--r-- 1 root root 4096 lis 14 13:08 cpb
-r-------- 1 root root 4096 lis 14 12:46 cpuinfo_cur_freq
-r--r--r-- 1 root root 4096 lis 14 12:18 cpuinfo_max_freq
-r--r--r-- 1 root root 4096 lis 14 12:18 cpuinfo_min_freq
-r--r--r-- 1 root root 4096 lis 14 12:46 cpuinfo_transition_latency
-r--r--r-- 1 root root 4096 lis 14 13:08 freqdomain_cpus
-r--r--r-- 1 root root 4096 lis 14 12:46 related_cpus
-r--r--r-- 1 root root 4096 lis 14 12:18 scaling_available_frequencies
-r--r--r-- 1 root root 4096 lis 14 12:18 scaling_available_governors
-r--r--r-- 1 root root 4096 lis 14 12:46 scaling_cur_freq          1400000
-r--r--r-- 1 root root 4096 lis 14 12:46 scaling_driver            acpi-cpufreq
-rw-r--r-- 1 root root 4096 lis 14 12:19 scaling_governor          userspace
-rw-r--r-- 1 root root 4096 lis 14 12:47 scaling_max_freq
-rw-r--r-- 1 root root 4096 lis 14 12:47 scaling_min_freq
-rw-r--r-- 1 root root 4096 lis 14 13:08 scaling_setspeed
drwxr-xr-x 2 root root    0 lis 14 12:20 stats
</code>

List current governors:
<code bash>
cat /sys/devices/system/cpu/cpu?/cpufreq/scaling_governor
</code>

<code>
cpufreqd.service                                                                                      loaded active running   LSB: start and stop cpufreqd
cpufrequtils.service                                                                                  loaded active exited    LSB: set CPUFreq kernel parameters
loadcpufreq.service                                                                                   loaded active exited    LSB: Load kernel modules needed to enable cpufreq scaling
</code>

<code>
/etc/init.d/cpufreqd
/etc/init.d/cpufrequtils
/etc/init.d/loadcpufreq
</code>

===== cpufreqd =====
Fully configurable daemon for dynamic frequency and voltage scaling
<code>
/etc/cpufreqd.conf
/etc/default/cpufreqd
</code>

===== cpufrequtils ======
It provides:
  * ''/etc/init.d/cpufrequtils''  - disabled by default (no file ``/etc/default/cpufrequtils``)
  * ''/etc/init.d/loadcpufreq''   - loads kernel modules
  * ''cpufreq-set''
  * ''cpufreq-info''
  * ''cpufreq-aperf''

''
utilities to deal with the cpufreq Linux kernel feature
 This package contains two utilities for inspecting and setting the
 CPU frequency through both the sysfs and procfs CPUFreq kernel
 interfaces.
 .
 By default, it also enables CPUFreq at boot time if the correct CPU
 driver is found.
''
<code>/etc/default/cpufrequtils</code>

==== change governor for all cpus ====

<code bash>
for ((i=0;i<$(nproc);i++)); do cpufreq-set -c $i -r -g powersave; done
</code>

Ansible one liner:
<code bash>
(cd .. && ansible pves -i $INVENTORY -a "bash -c 'for ((i=0;i<\$(nproc);i++)); do cpufreq-set -c \$i -r -g powersave; done'" --become)
</code>