Feature request: C-states & P-states support

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t27049215
Posts: 2
Joined: Sun Jun 08, 2014 3:36 pm

Feature request: C-states & P-states support

Post by t27049215 »

Hi,
I was setting up my fitpc4 recently, running Arch linux (linux 3.14.5-1)

I noticed that CPU is always running at full speed, and my box stays idle 99% of the time, so I tried loading acpi-cpufreq module to lower the CPU frequency, and it failed
If I'm correct, it's because BIOS doesn't support C-states & P-states

I hope to see this feature supported in future BIOS update

roblucid
Posts: 9
Joined: Sun Apr 29, 2012 2:17 pm

Re: Feature request: C-states & P-states support

Post by roblucid »

I find this surprising as the fit PC3 I have does have freq scaling out of the box on openSUSE, upgrading from 3.11 to 3.13 & up, enables the Radeon DPM features further reducing power. I've upgraded to 3.15 recently and my AMD Bobcat drops to 825 Mhz at idle, 1/2 the rate of the core that's got full load generating primes.

As Linux is supported, I would expect the Bios to be checked. I have experienced distro kernels, having poor defaults in past, which affected CPU scaling, Intel were big on "race to idle" a few years back, so it may be kind of thing that slips through. Anyway you can check Arch on another AMD box?

t27049215
Posts: 2
Joined: Sun Jun 08, 2014 3:36 pm

Re: Feature request: C-states & P-states support

Post by t27049215 »

@roblucid
I don't have another fitpc to test Arch on.
FYI, there is some news on this topic: http://www.fit-pc.com/wiki/index.php/Fi ... sion_Notes

It seems more like a hardware issue than a software one. :(
If only my rev1.1 board could have this "Power consumption optimization" too...


UPDATE: It's not a hardware issue, a new BIOS update is available, see: http://www.fit-pc.com/wiki/index.php/Fi ... _ROM_Files

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