user undervolting

Message

marcogrego · Post by **marcogrego** » Tue Mar 11, 2008 1:48 pm

thank you so much that worked great!

marcogrego · Post by **marcogrego** » Tue Mar 11, 2008 2:52 pm

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.

pierrestz · Post by **pierrestz** » Wed Mar 26, 2008 11:42 pm

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 18)
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 · Post by **albright** » Tue Apr 01, 2008 12:27 pm

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?

marcogrego · Post by **marcogrego** » Tue Apr 01, 2008 1:42 pm

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.

jannis · Post by **jannis** » Sat May 17, 2008 4:38 pm

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 · Post by **jannis** » Thu May 22, 2008 4:32 pm

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

legrosmaxou · Post by **legrosmaxou** » Thu Jun 19, 2008 10:05 am

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 ?

marcogrego · Post by **marcogrego** » Thu Jun 19, 2008 3:06 pm

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

legrosmaxou · Post by **legrosmaxou** » Sat Jun 21, 2008 1:07 pm

where would it find the tables then ?

Schwinni · Post by **Schwinni** » Thu Aug 21, 2008 11:16 am

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-p ... src/gentoo

Best regards,
Chris

.yankee · Post by **.yankee** » Thu Feb 05, 2009 4:32 pm

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

Code: Select all

* sys-power/cpuspeedy
     Available versions:  0.4.1
     Homepage:            http://cpuspeedy.sourceforge.net/
     Description:         A simple and easy to use program to control the speed and the voltage of CPUs on the fly.

* sys-power/powernowd
     Available versions:  0.90 ~0.96 0.97
     Homepage:            http://www.deater.net/john/powernowd.html
     Description:         Daemon to control the speed and voltage of CPUs

albright · Post by **albright** » Thu Feb 05, 2009 9:26 pm

* sys-power/cpuspeedy
* sys-power/powernowd

those are good programs but the point of undervolting is to
lower the voltage of the processor at GIVEN speed. For
example, my centrino ran at 600mhz at stock 7.6 v; with
undervolting I run at 600mhz at 7 v. The programs above
can't do that so far as I know. They are doing a different
job.

.yankee · Post by **.yankee** » Thu Mar 12, 2009 12:03 am

albright wrote: those are good programs but the point of undervolting is to
lower the voltage of the processor at GIVEN speed. For
example, my centrino ran at 600mhz at stock 7.6 v; with
undervolting I run at 600mhz at 7 v. The programs above
can't do that so far as I know. They are doing a different
job.

Actually, as I took a look at their websites, there seems to be NOTHING about manipulating the voltage in any of those! Sorry, if I mislead someone - it just seems the ebuild descriptions are very misleading themselves.

schorsche · Post by **schorsche** » Sun Aug 23, 2009 9:35 am

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?

user undervolting

how many frequencies does my pentium M support for scaling?

intel enhanced speedstep

changing frequencies for banias