Arch Linux

dwidmann

Member

From: Gordonsville, Virginia, US

Registered: 2009-05-27

Posts: 60

question about cpu scaling/power saving

For a while now I've noticed that my laptop has been running hot ([link=https://ark.intel.com/content/www/us/en/ark/products/149091/intel-core-i7-8565u-processor-8m-cache-up-to-4-60-ghz.html]cpu[/link] ~53C) , fan runs continuously, etc. I seem to have found the root of the issue:

when using the (default?) intel_pstate cpu governing driver, the cpu frequency sits at around 3.2GHz when completely idle, with min/max of 400MHz/4.6GHz (matches max turbo freq for chip), a nominal frequency of 1.8GHz, and the 'powersave' governor in use.

I rebooted with intel_pstate=disabled, and made sure acpi_cpufreq driver is used, with the schedutil governor enabled. It now reports frequencies as low as ~1GHz when completely idle, but min/max range has shrunk to 800MHz/2GHz (which matches the tdp-up/tdp-down freqs for the chip).

The upside is that it is running at a much more comfortable ~42C idle, but am I losing out on Turbo? Are these the expected results / how can I get better (i.e. aggressively scales clock back to near minimum frequency when idle, scales up towards max in some sane manner) Please advise.

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"I refuse to be part of a society that encourages the rampant abuse of its own language." ~ BM

adamlau

Member

Registered: 2009-01-30

Posts: 418

Re: question about cpu scaling/power saving

You should be fine. I boot up into schedutil and it pushes two cores to turbo frequencies when compiling a kernel and multiple cores when compiling multiple kernels. I manually set the governor between schedutil and performance depending on the expected/current workload for desktop use.

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