I think this was something that we all made mistake, adding
intel_pstate=disableinto grub command-line, seeing it open more CPU Frequencies to choose, and then thinking that it "unlocked" the frequencies. I used to believe the same, until I read more about these I realized that it was not. It's not "unlock" anything, it just switching
intel_pstateto a general cpu-freq scaling driver called
So let's start to find out what is CPUFreq. According to a post by Lenovo
source : https://lenovopress.com/lp0826.pdfCpufreq, also referred to as CPU frequency scaling or CPU speed scaling, is the infrastructure in the Linux kernel space that enables users to scale the CPU frequency in order to save power.
On Intel CPUs, there are 2 CPUFreq drivers that control the power :
intel_pstateis a CPUFreq driver made by Intel, support from Sandy Bridge (Intel 2nd Gen) and above while acpi-cpufreq is a generic one, used in most of the CPUs including AMD one.
So what's the difference between those two ? Well.... you can clearly see that intel_pstate limit the control or what the tweaking of your CPU while acpi_cpufreq gave you the full control of the frequencies, clocking control (but no overclock, just in a limit). intel_pstate got 2 main governors : performance and powersave - the name say it all for your purpose (from kernel 5.7 Intel started to add schedutil so we got 3), acpi_cpufreq on the other hand gave you the linux kernel's governors you see on devices like Android including : performance, schedutil, powersave, ondemand and conservative.
Ok now you know the difference between the two, but you may wanna ask : How are these two perform ?
On Android, so far no one made a scientific or detail benchmark. But on Linux, Phoronix has covered it for a couple of times now.
there is also a post by Percona in 2016 benchmarking intel_pstate and acpi_cpufreq
In this blog, we'll examine how CPU governor performance affects MySQL.
Both ACPI and Intel_pstate “performance” governor shows the best (and practically identical) performance
In short, it doesn't matter if you disable intel_pstate or not if you only use Performance governors. You are just switching from what Intel think you should do, to you decide on your own.
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