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cs:frequency_scaling [2019/04/04 16:02] (current)
zioskenz created
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 +====== Frequency scaling ======
 +===== How to disable frequency scaling =====
 +This guide explains an easy way to disable **frequency scaling**.
 +
 +First thing to do is to check the number of CPUs in the system with the command:
 +<code bash>
 +ls /​sys/​devices/​system/​cpu/​
 +</​code>​
 +The provided output will be something like this:
 +<code bash>
 +cpu0  cpu2  cpuidle ​      ​kernel_max ​ modalias ​ online ​   power    uevent
 +cpu1  cpu3  intel_pstate ​ microcode ​  ​offline ​  ​possible ​ present
 +</​code>​
 +and in this case the number of physical CPUs for which we can disable frequency scaling is four, namely ''​cpu0'',​ ''​cpu1'',​ ''​cpu2''​ and ''​cpu3''​.
 +
 +With the following script executed by with the //root// privilege:
 +<code bash>
 + for i in $(seq 0 3) ; do echo "​performance"​ > /​sys/​devices/​system/​cpu/​cpu3/​cpufreq/​scaling_governor;​ done
 +</​code>​
 +we can set the ''​performance''​ governator policy, which disable frequency scaling. We used ''​$(seq 0 3)''​ because we have 4 CPUs, from ''​cpu0''​ to ''​cpu3''​. In a system with 8 physical cores, the correct command would have been ''​$(seq 0 7)''​. Remember that the script must be re-executed each time the system is restarted.
 +
 +To check that frequency scaling is effectively disabled, you can type many times the following command checking that the frequencies of your CPUs are fixed to the highest values:
 +<code bash>
 +cat /​proc/​cpuinfo
 +</​code> ​
 +
 +
  

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