# Dynamic voltage and frequency scaling

Source: [https://docs.qualcomm.com/doc/80-70014-30/topic/dcvs.html](https://docs.qualcomm.com/doc/80-70014-30/topic/dcvs.html)

Dynamic voltage and frequency scaling (DVFS) management is a technique used to switch
        the CPU core frequency based on load requirement. This helps to balance power, performance,
        and thermal behavior of the platform.

![](data:image/png;base64,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)

Figure : DVFS workflow

For more information on DVFS, see [index: kernel/git/torvalds/linux.git](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/cpu-freq?h=v6.6).

For example, if the available CPU frequencies are 1 GHz, 1.5 GHz and 2 GHz and the
            application needs to run at 1 GHz, then the maximum frequency of the CPU should be
            maintained at 1 GHz. This ensures the right utilization of CPU frequency, and its
            voltage helping to optimize CPU power while maintaining performance.

## CPU frequency scaling tunables

The following table lists the commands used to tune CPU frequency for balanced power,
                and performance:

Table : Commands to tune CPU frequency

| Commands | Explanation |
| --- | --- |
| cat /sys/devices/system/cpu/cpufreq/policy<x>/scaling_cur_freqCopy to clipboard | Reads the existing CPU frequency |
| cat /sys/devices/system/cpu/cpufreq/policy<x>/scaling_available_frequenciesCopy to clipboard | Reads the supported frequency |
| cat /sys/devices/system/cpu/cpufreq/policy<x>/scaling_min_freqCopy to clipboard | Reads the supported minimum CPU frequency |
| echo <cpu freq in KHz> > /sys/devices/system/cpu/cpufreq/policy<x>/scaling_min_freqCopy to clipboard | <ul class="ul" id="dcvs__ul_cdf_1bp_wbc"><br>                                    <li class="li">Sets the minimum CPU frequency</li><br><br>                                    <li class="li">Overwrites existing CPU minimum frequency</li><br><br>                                    <li class="li">Sets any frequency from<br>                                            <code class="ph codeph">scaling_available_frequencies</code><br>                                    </li><br><br>                                </ul> |
| cat /sys/devices/system/cpu/cpufreq/policy<x>/scaling_max_freqCopy to clipboard | Reads the maximum frequency |
| echo <cpu freq in KHz> > /sys/devices/system/cpu/cpufreq/policy<x>/scaling_max_freqCopy to clipboard | <ul class="ul" id="dcvs__ul_gnm_33p_wbc"><br>                                    <li class="li">Sets the maximum supported CPU frequency</li><br><br>                                    <li class="li">Overwrites existing maximum CPU frequency</li><br><br>                                    <li class="li">Sets any frequency from<br>                                            <code class="ph codeph">scaling_available_frequencies</code></li><br><br>                                </ul> |

Note: `<x>` refers to 0, 4, 7
- 0 is for Silver cluster
- 4 is for Gold cluster
- 7 is for Prime cluster
- Unit for frequency is KHz

Any modifications made through `SSH` commands will revert to
                    their default values upon platform reset.

**Parent Topic:** [CPU power management](https://docs.qualcomm.com/doc/80-70014-30/topic/cpupowermanagement.html)

Last Published: Jul 15, 2024

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