user undervolting

marcogrego · n00b Joined: 10 Mar 2008 Posts: 5

thank you so much that worked great!
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marcogrego · n00b Joined: 10 Mar 2008 Posts: 5

Hey folks,
I have a pentium M 715 Dothan @1.5GHz
and it supports only two frequencies:

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
1500000 600000

cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver
acpi-cpufreq

Does anybody have the same issue? AFAIK it's quite unlikely, or to be precise, rare to have only 2 frequencies available for frequency scaling... I also used the module speedstep-centrino unsuccesfully.
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pierrestz · n00b Joined: 26 Mar 2008 Posts: 1

Hi
I have a Pentium-M Sonoma 1.73Ghz processor and undervolting works well with phc 0.3.1 + speedstep-centrino on kernel 2.6.22

But i have some cpu freezes in ondemand mode when i set different voltage for the 3 highest frequency.
For example vids : 25 25 25 2 works with the ondemand governor (factory default : 41 32 25 1

but other choices for the 3 first voltages gives a cpu freeze.
That's strange because with userspace governor i can set (in continuous) more efficient and specific voltage for each step : 23 17 11 2 but it freezes when i put the ondemand governor...

Is it a known bug ?

also it's the 1st time i can get the undervolting working : it fails with patched acpi-cpufreq.ko

albright · Posted: Tue Apr 01, 2008 12:27 pm Post subject:

I see in kernel 2.6.24-r4 that Intel Enhanced SpeedStep
is deprecated. What - if any - implications has this for
linux-phc? I take it that for now at least I have to keep
using the enhanced speedstep for underclocking?
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marcogrego · n00b Joined: 10 Mar 2008 Posts: 5

you're right it is deprecated, and as such you will have to use acpi-cpufreq (or something similar), this works fine with the undervolting process.
Additionally you can take advantage of the Intel speedstep technology by using the module mentioned above without being obliged to use the old one.

ps: the underclocking is implied by the speedstep itself which decreases the clock speed dynamically according the clock frequencies set available for your cpu.
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jannis · Posted: Sat May 17, 2008 4:38 pm Post subject:

Just my experience with undervolting using phc:

I've got a Core 2 Duo T5500 running 2.6.23-gentoo right now and undervolting works (changed 1,66GHz VID from 40 to 19 and 1,33GHz VID from 30 to 19) but it won't let me go below 19 which is the default VID for 1,00GHz. My machine is running in 64bit mode and the maximum Core-Temp has changed from about 71°C to 58°C

jannis · Posted: Thu May 22, 2008 4:32 pm Post subject:

Anyone knows how to get a Core 2 Duo below VID 19?

legrosmaxou · n00b Joined: 09 May 2006 Posts: 7

I am using a Banias 1500 , I d like to directly change the frequency tables in the kernel sources.
In the old versions it was possible in the centrino module, but no that it is integrated in the acpi driver I cant find the tables.

any help ?
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marcogrego · n00b Joined: 10 Mar 2008 Posts: 5

I dont think it's possible. As fas as I know It was with the old module "speedstep-centrino", the new one does not include any specific section for what you are trying to do.

IMHO
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legrosmaxou · n00b Joined: 09 May 2006 Posts: 7

where would it find the tables then ?
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Schwinni · Posted: Thu Aug 21, 2008 11:16 am Post subject:

The tables are in the ACPI P-States driver.

PHC-0.3.2 can patch gentoo-sources-2.6.26 successfully.
Find the patch here:
http://phc.athousandnights.de/viewtopic.php?f=13&t=2

The VID/frequency pairs can be found in /sys/devices/system/cpu/cpu<n>/cpufreq/phc_controls.

For Pentium-M processors you can use VID = (Vcc - 700) / 16 <=> Vcc = (VID * 16) + 700 to calculate the voltage for a certain VID.

Use these scripts to start/stop and config the undervolting:
https://www.dedigentoo.org/trac/linux-phc/browser/trunk/src/gentoo

Best regards,
Chris

.yankee · Apprentice Joined: 24 Feb 2008 Posts: 194 Location: Polska

For those of you, who haven't searched the portage recently and would like to try a ready program:

albright · Posted: Thu Feb 05, 2009 9:26 pm Post subject:

.yankee · Apprentice Joined: 24 Feb 2008 Posts: 194 Location: Polska

schorsche · Apprentice Joined: 27 Jan 2005 Posts: 230

Hello there,

I downloaded the newest phc-patch for gentoo kernel 2.6.30 from
http://www.linux-phc.org/forum/viewtopic.php?f=13&t=2

It patches fine and the voltage stepping works after rebooting into
the newly compiled kernel.
However,
/sys/devices/system/cpu/cpu<n>/cpufreq/phc_controls

shows only two available frequencies, that is the highes (1500MHz)
and the lowest (600 MHZ) frequency on my laptop.
What has happened with all the freq-steps in between?