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| cab8a9 | Anonymous | 2026-01-31 00:06:22 | 1 | # Cpu Frequency Scaling |
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| 3 | **The CPU frequency scaling feature present in modern computers allows lowering and increasing the processor speed dynamically in runtime so as to save energy while having the possibility of increasing the performance and power consumption if needed. Activating CPU frequency scaling under Slackware is very easy, and requires loading a minimum of two kernel modules and running a simple command. On the one hand, you need to load a specific CPU driver that will activate the frequency scaling feature in your platform. Second, you need to choose a CPU frequency scaling governor, a module that will decide how and when to change the internal processor speed. There are governors to always run at full speed, governors to always run at low speed, governors to increase and decrease the speed based on the CPU load, etc.** |
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| 7 | __Find available governors__ |
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| 9 | <code>cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_available_governors</code> |
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| 12 | __Setting a governor__ |
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| 14 | <code>nano /etc/default/cpufreq</code> |
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| 16 | __Applying the governor__ |
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| 18 | make rc.cpufreq executable |
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| 20 | <code>chmod +x /etc/rc.d/rc.cpufreq</code> |
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| 21 | make sure its running |
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| 23 | <code>/etc/rc.d/rc.cpufreq restart</code> |
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| 26 | __Governor types__ |
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| 28 | **Performance** |
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| 30 | The CPUfreq governor "performance" sets the CPU statically to the |
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| 31 | highest frequency within the borders of scaling_min_freq and |
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| 32 | scaling_max_freq. |
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| 35 | **Powersave** |
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| 37 | The CPUfreq governor "powersave" sets the CPU statically to the |
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| 38 | lowest frequency within the borders of scaling_min_freq and |
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| 39 | scaling_max_freq. |
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| 42 | **Userspace** |
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| 44 | The CPUfreq governor "userspace" allows the user, or any userspace |
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| 45 | program running with UID "root", to set the CPU to a specific frequency |
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| 46 | by making a sysfs file "scaling_setspeed" available in the CPU-device |
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| 47 | directory. |
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| 50 | **Ondemand** |
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| 52 | The CPUfreq governor "ondemand" sets the CPU frequency depending on the |
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| 53 | current system load. Load estimation is triggered by the scheduler |
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| 54 | through the update_util_data->func hook; when triggered, cpufreq checks |
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| 55 | the CPU-usage statistics over the last period and the governor sets the |
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| 56 | CPU accordingly. The CPU must have the capability to switch the |
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| 57 | frequency very quickly. |
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| 60 | **Conservative** |
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| 62 | The CPUfreq governor "conservative", much like the "ondemand" |
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| 63 | governor, sets the CPU frequency depending on the current usage. It |
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| 64 | differs in behaviour in that it gracefully increases and decreases the |
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| 65 | CPU speed rather than jumping to max speed the moment there is any load |
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| 66 | on the CPU. This behaviour is more suitable in a battery powered |
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| 67 | environment. |