CPU frequency scaling.

comicosmos · 2011-05-26 14:03:36

First of all, by reading this wiki page https://wiki.archlinux.org/index.php/CP … cy_Scaling I am able to modprobe acpi_cpufreq and choose frequency or use governer.
But there are too few frequency choices.

I have two laptops on hand.
The first one is fairly old, with Intel centrino dothan 725 1.6GHz single core cpu. In the past, I had win xp on the machine. There's an app RMClock, which give me tens pairs of frequency/voltage, if not handreds. I can either manually choose a freq from (0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6)GHz and a vast voltage range that I cannot remember, or use predefined policies such as max power, max saving, balanced auto scaling...
But in Linux I can only see two freq (0.6, 1.6)GHz. 0.6G is not sufficient while 1.6G make fans noisy and machine hot.
I googled for solutions. There's patched version speedstep_centrino.c which will provide more freq choices. But this was deprecated and rejected by upsteam. very old story. (http://help.lockergnome.com/linux/Ubuntu-PATCH-Add-Dothan-frequency-tables-speedstep--ftopict366266.html || http://pastebin.com/UPiba4FP)
Besides I knew little about C programming and don't know how to compile a single module the modprobe it. I don't want to use AUR kernels because there may be potential dependencty issue. Arch updates a lot.
The other PC with Intel T5200. I can see only 3 freq. I just cannot believe that T5200 only offers 3 freq!!

For the older one it may be BIOS probmes or bugy ACPI, but several years later when T5200 comes out, there's still bugy BIOS or bugy ACPI issue? Why I would be that lucky to have two bugy hardware? At this point I would consider it is the ACPI module problem.
Anyone can help me to find out the missed freq as easy as possible, just like "launch the app RMClock and you get more choices in Win XP"? Maybe compile a kernel module, how to? No AUR kernel, please.

twilight0 · 2011-05-26 14:18:24

There is a utility in AUR called trayfreq. Intall it and you can choose the ondemand policy, performance or whatever frequency you like.

comicosmos · 2011-05-27 12:19:09

I alerady used trayfreq. It only an GUI frontend that communicate with acpi_cpufreq. The problem is, it should offer more freq.

Thanks anyway.

lukaszan · 2011-05-27 12:38:06

I might be wrong, but I always thought that the steps are hardware specific (i.e. depend on the CPU and not OS/software).

comicosmos · 2011-05-28 09:40:20

Yes I totally agree that steps are hardware dependent.

But at present Linux(at least the default config) kernel module is not good enought to manipulate these features.
For my paticular case, in win xp I have many steps choices, but in Linux I see fewer, and that's the problem.

graysky · 2011-05-28 10:11:23

Practically, why do you need more than a few frequencies? For example, you're idle. I would want the lowest freq. You're under load. I would want the highest frequency. For situations in between, say launching a program, or moving data, whatever, an intermediate frequency would be fine. What do you hope to achieve with a more refined list of available frequencies?

lukaszan · 2011-05-28 10:37:08

graysky wrote:

Practically, why do you need more than a few frequencies? For example, you're idle. I would want the lowest freq. You're under load. I would want the highest frequency. For situations in between, say launching a program, or moving data, whatever, an intermediate frequency would be fine. What do you hope to achieve with a more refined list of available frequencies?

I agree, your CPU, in practice, is really either idle or loaded.

In my case (AMD 965, 4 freq steps) the processor is at lowest freq for about 90 - 95% of a time, and at highest for 5 - 10%. The 2 intermediate are used for about 0.1% of a time.

My guess would be that intermediate ones are only used for smooth transition from lowest to highest. So they really are hardware dependent...

demian · 2011-05-28 10:40:04

the heart wants what the heart wants

comicosmos · 2011-06-07 13:41:22

well, for my case the lowest freq is not power enough and the highest freq always makes the fan noising.

To be specific, in XP I am able to set the lower limit to 1.2GHz.
But in Linux I have only two choices, either 0.6GHz or 1.6GHz.

Arch Linux

#1 2011-05-26 14:03:36

CPU frequency scaling.

#2 2011-05-26 14:18:24

Re: CPU frequency scaling.

#3 2011-05-27 12:19:09

Re: CPU frequency scaling.

#4 2011-05-27 12:38:06

Re: CPU frequency scaling.

#5 2011-05-28 09:40:20

Re: CPU frequency scaling.

#6 2011-05-28 10:11:23

Re: CPU frequency scaling.

#7 2011-05-28 10:37:08

Re: CPU frequency scaling.

#8 2011-05-28 10:40:04

Re: CPU frequency scaling.

#9 2011-06-07 13:41:22

Re: CPU frequency scaling.

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