ThinkWiki - User contributions [en]

Template:CodeHeader

2006-09-04T11:02:53Z

Gravix: /* Discussion */

*Filename: <tt style="font-size: 125%">'''{{{filename}}}'''</tt> 
*Context: {{{context}}} 
*Author(s): {{{author}}} 
*License: {{{license}}} 

*[{{ArticleRawLink}} Download code] (manually save this as <tt>'''{{{filename}}}'''</tt>)
*[{{ArticleEditLink}} Edit code]
*[{{ArticleHistoryLink}} Code revision history]

[[Category:Code]]

{{HINT_float|25em|Wondering about this sourcecode posting convention? See [[:Category:Code]].}}

=Discussion=

Does anyone know why this script eats up so much CPU time? It bumps my CPU up to 40% utilization every time it updates, which is set to every 3 seconds by default. I knocked it down to updating every 30 seconds and I think that will be okay, but it just seems a little odd.

How to control fan speed

2006-09-04T10:47:59Z

Gravix: slight update to R51 fan values

This page discusses methods for controlling the system fan.

==For Linux==
===Using a patched kernel===

The [[Patch for controlling fan speed]] provides a convenient interface via {{path|/proc/acpi/ibm/fan}}.

Manual speed control can be done through the [[patch for controlling fan speed]]:

'''#cat /proc/acpi/ibm/fan'''
status: enabled
level: auto
speed: 4219
commands: enable, disable, level <level>
(<level> is 0-7, auto or disengaged)

'''#echo level 2 > /proc/acpi/ibm/fan'''

'''#cat /proc/acpi/ibm/fan'''
status: enabled
level: 2
speed: 3142
commands: enable, disable, level <level>
(<level> is 0-7, auto or disengaged)

===Using a stock kernel===

If you have the [[ibm-acpi]] module loaded with <tt>experimental=1</tt>, you can control the fan without patching the kernel by directly writing to the relevant embedded controller register using {{path|/proc/acpi/ibm/ecdump}}.

For example:

{{cmdroot|echo 0x2F 0x00 > /proc/acpi/ibm/ecdump}} (fan off)

{{cmdroot|echo 0x2F 0x02 > /proc/acpi/ibm/ecdump}} (low speed)

{{cmdroot|echo 0x2F 0x04 > /proc/acpi/ibm/ecdump}} (medium speed)

{{cmdroot|echo 0x2F 0x07 > /proc/acpi/ibm/ecdump}} (maximum speed)

{{cmdroot|echo 0x2F 0x80 > /proc/acpi/ibm/ecdump}} (automatic - default)

{{cmdroot|echo 0x2F 0x40 > /proc/acpi/ibm/ecdump}} (disengaged)

Ssee the specifications below for the meaning of these modes.

===On/off control using stock kernel===

If you only wish to turn the fan on and off (with automatic control when it's on), you can use the following.

When loading [[ibm-acpi]] v0.11 with experimental switch ({{cmdroot|1=modprobe ibm_acpi experimental=1}}), it is possible to read and write the status of fan:

'''#cat /proc/acpi/ibm/fan'''
status: enabled
speed: 3580
commands: enable, disable

'''#echo disable > /proc/acpi/ibm/fan'''

'''cat /proc/acpi/ibm/fan'''
status: disabled
speed: 0
commands: enable, disable

When off, the fan will then '''never''' wake up. It is advised to use an automated control script to reduce the chance of hardware damage.

===Automated control scripts===

An [[ACPI fan control script#Variable speed control scripts|ACPI fan control script]] can be to override the firmware's fan algorithm with gentler, quieter version. It monitors the laptop's [[thermal sensors]] and sets the fan speed accordingly, according to customizable thresholds. For the default behavior, simply save the [[ACPI fan control script#Variable speed control scripts|script]] as {{path|tp-fancontrol}} and run 
{{cmdroot|./tp-fancontrol}}

==For Windows==

Shimodax's ThinkPad fan control tool offers similar functionality (see [http://forum.thinkpads.com/viewtopic.php?t=17715 forum discussion] at thinkpads.com). Source and binaries are available through the [http://sourceforge.net/projects/tp4xfancontrol "Tp4xFanControl"] project on SourceForge.

==Hardware specs==

The patch relies on the following hardware behavior, which was discovered experimentally by [[User:Thinker|Thinker]] and neither provided by nor confirmed by IBM/Lenovo. The following description may be inaccurate and may vary by model (see list of models above). The terminology probably does not match the one used by IBM/Lenovo engineers.

ACPI DSDT register _SB.PCI0.LPC.EC.HFSP (8 bits, offset 0x2F in the <tt>EmbeddedController</tt> address space, accessed through the standard EC interface at IO ports 0x62 and 0x66) is read/writable and has the following meaning:

Bits 7 6 5 4 3 2 1 0
---------------
Value 1 0 * * * * * * - automatic
* 1 * * * * * * - disengaged
0 0 N N N N N N - manual (0..63; 0=disable fan, 1=min, ..., 7=max)

In ''automatic'' mode, the embedded controller sets the fan speed automatically according to system temperatures and some unknown algorithm.

In ''manual'' mode, the fan level is forced to the given value and the EC will auto-regulate the fan to maintain at a (roughly) constant RPM, which is model-dependent. Manual speed levels 8-63 yield the same behavior as level 7, and the the ACPI DSDT uses level 7 for the emergency mode it enters upon critical CPU/GPU temperature, so apparently 7 is the real maximum level.

In ''disengaged'' mode, the embedded controller does not read the fan RPM (hence <tt>EmbeddedController</tt> offset 0x84 is not updated), and does not maintain a stable fan speed. When disengaged mode is entered the fan speed is not immediately changed (except if the fan was disabed, in which case it is turned on at a low level). However, once in disengaged mode, fan speed will slowly increase to ''beyond'' the maximum manual level (this may cause hardware damage!).

After boot, the register may not reflect the true state of the EC (on some models it reads 0x07 even though the EC is actually in automatic mode).

{{HINT|Apparently the [[Problem with fan noise|pulsing fan noise]] experienced by some users can be cured by repeatedly running 2-4 seconds of manual control followed by 0.5-1 seconds of disengaged mode. The pulse occurs when the the embedded controller computes the fan speed and adjusts the fan voltage adaptively every few seconds (~4.8sec for the ThinkPad T43); the aforementioned mode switching doesn't give it a chance to do so. One of the [[ACPI fan control script#Variable speed control scripts|ACPI fan control scripts]] implements this solution.}}

==Supported models==

The above was successfully tested on the following models:

* ThinkPad {{T43}}, {{T43p}} (fan levels RPM: 1-2 = ~3300, 3-5 = ~4100, 6-7 = ~4700; disengaged mode works)
* ThinkPad {{T42}}, {{T42p}} (fan levels RPM: 1-2 = ~2900, 3-5 = ~3700, 6-7 = ~4700; disengaged mode works at ~5200)
* ThinkPad {{T41}}, {{T41p}} (fan levels RPM: 1-2 = ~2980, 3-5 = ~3500, 6-7 = ~4050; disengaged mode works at ~5100)
* ThinkPad {{T40}} (fan levels RPM: 1-2 = ~2950, 3-5 = ~3600, 6-7 = ~4050)
* ThinkPad {{T30}}
* ThinkPad {{T22}}
* ThinkPad {{T23}} (low speed = ~2200, medium and maximum speed = ~4800; disengaged mode works at ~5800)
* ThinkPad {{R52}}
* ThinkPad {{R50}} (highest manual level is 3; disengage mode works and reaches much higher RPM)
* ThinkPad {{R50p}} (disengaged mode works at ~5100)
* ThinkPad {{R51}} (level 0 = off, level 1-2 = ~3150, level 3-5 = ~3350, level 6 = ~3750, disengaged = ~5100)
* ThinkPad {{X40}}
* ThinkPad {{X41T}}
* ThinkPad {{X31}}
* ThinkPad {{Z60t}} (fan levels RPM: 1-2 = ~1700, 3-5 = ~2800, 6-7 = ~3500)
* ThinkPad {{Z60m}} (fan levels like Z60t)
* ThinkPad {{X60}}
Probably other models are supported too (please update this page if you confirm this).

==Models using a different interface==

The following models also work, use a different access method which supported (only) via the {{path|/proc/acpi/ibm/fan}} of [[ibm-acpi]]. No need for patching.

* ThinkPad {{600E}}, {{600X}}, {{770E}}, {{770X}} (these use a different fan control interface)

==Unsupported models==

* ThinkPad {{560}} (these models don't have a fan)

Rovclock

2006-09-04T07:34:10Z

Gravix: /* Minimum stable clockrates */

==General==
Rovclock is a utility to control frequency rates of your Radeon card.

It is very helpful for underclocking the Radeon chip in order to save power when running on batteries. Also, by underclocking it is possible to prevent the fan from running.

It can also be used to gain performance by overclocking.

{{NOTE|While this utility complements the [[How to make use of Graphics Chips Power Management features|DynamicClocks]] option of the X.org <tt>radeon</tt> driver, it is not compatible with the power saving mode of the [[fglrx]] driver. Setting power saving mode using both [[fglrx]] and [[rovclock]] results in an unusably slow desktop.}}

==Features==
Used to under-/overclock Radeon gfx-cards.
* Controls GPU core frequency
* Controls gfx-memory frequency

== Project Homepage / Availability ==
* Homepage: http://www.hasw.net/linux/

==Usage==
*Set the core frequency (-c) to 100 Mhz and the memory frequency (-m) to 120 Mhz.
:{{cmduser|sudo rovclock -c 100 -m 120}}
*Get current frequencies among other information (-i).
:{{cmduser|sudo rovclock -i}}

==Minimum stable clockrates==
* {{A30p}} with Radeon 7000
** LCD: No lower core limit, 90MHz mem (basic use) / 125MHz mem (no artifacts with glxgears)
* {{T42}} with Radeon 7500 NOTE: Setting the memory under 100Mhz may hang your card.
** LCD: 100MHz core, 120MHz memory.
** Using DVI output on Port replicator: 100Mhz core, 180MHz memory.
* {{T42}} with Radeon 9600
** LCD: Core: 54.0 MHz, Mem: 60.75 MHz
* {{T42p}} Firegl T2 (9600), fglrx driver
** 1600x1200 LCD: Core: 81 Mhz, Mem: 67.5 Mhz
* {{T43}} with [[ATI Mobility Radeon X300]]:
** 100MHz core, 120Mz memory (see more [[ATI Mobility Radeon X300|here]])
* {{X31}} with ATI Radeon Mobility M6 LY:
** 90MHz core, 100Mz memory (90/90 is giving distorted picture)
* {{R50p}} with FireGL Mobility T2:
** 1600x1200 LCD: Core: 100 MHz Mem: 120Mz
* {{R51}} with FireGL 9000
** Core: 40 Mhz Mem: 100 Mhz (2d only, reducing memory further causes some artifacts and doesn't visibly reduce temps.)

== See also ==
*[[How to make use of Graphics Chips Power Management features]] using the <tt>DynamicClocks</tt> option of the <tt>radeon</tt> driver
*[http://forums.gentoo.org/viewtopic-t-343029.html Gentoo forum discussion]
*[[Radeontool]]

[[Category:Tools]]

Pentium M undervolting and underclocking

2006-09-04T05:53:54Z

Gravix: /* Instructions */

== Background ==

Intel Pentium M processors from the [[Intel Pentium M (Dothan)|Dothan]] and [[Intel Pentium M (Banias)|Banias]] families can be instructed to operate at voltage and clock frequencies lower than the nominal ones recommended by Intel and used by ThinkPads by default. Experience shows that the processor may continue working correctly at lower-than-nominal voltages and frequencies, thereby reducing power consumption, heat and fan noise.

In the Pentium M, speed and voltage are controlled by software (through the MSR registers). It is up to the operating system to choose the right voltage for each frequency. Normally this is done according to tables published by Intel or according to ACPI tables. However, this can be overriden - in the case of Linux, by a kernel patch.

{{WARN|Following this instructions will operate your CPU under conditions it was not designed for. Even if your system seems stable, it may still suffer transient faults leading to arbitrary data corruption. In addition, errors in following these instructions (or changes between processor models) may operate the CPU ''above'' its nominal parameters, which, if taken too far, can cause kernel panics or even possibly hardware damage}}

For an example of what may be achieved, consider these examples: when voltages on one ThinkPad {{T43}} were reduced by 20-30%, stable CPU temperature dropped by 7-10deg under both idle and burn-in conditions. Combined with [[how to control fan speed|fan speed control]], this greatly reduced the [[Problem with fan noise|problem with fan noise]]. On one user's ThinkPad {{R51}}, an undervolt brought the full-load processor temperature down from 87 degrees to 63 degrees while maintaining full stability. The effect was, however, negligible at idle.

{{NOTE|While under''volting'' has a clear measurable effect, it's not clear if under''clocking'' really works. <tt>/proc/cpuinfo</tt> reflects the underclocked frequency, but enabling debug output on <tt>cpufreq</tt> causes it to say things like "<tt>CPU frequency out of sync: cpufreq and timing core thinks of 533000, is 800000 kHz.</tt>" where the former is the chosen underclocked frequency and the latter is the documented minimum frequency. This discrepancy also causes [[Software Suspend 2]] to oops during suspend.}}

There are several methods to control CPU voltage in Linux, and currently all of them require a patched kernel.

== Alternative 1: patch with hard-coded voltages ==
=== Instructions ===

# Determine the stable voltages for each frequency, using some overclocking/undervolting utility that has specific support for Pentium M ("Centrino") processors. It seems that no such utility exists for Linux. For windows, one good choice is [http://www.pbus-167.com/chc.htm Notebook Hardware Control (NHC)], which conveniently also includes a table of nominal frequencies and voltages (in its help file). Ascertain that at the undervolted settings the CPU actually performs correct computation ([http://www.mersenne.org/freesoft.htm Prime95] in "Tortute Test" mode seems to be a good partial test emphasizing FPU and memory access). Note that beside reducing voltages (undervolting), you can also try to add lower frequencies (underclocking). If you undervolt a particular frequency too much your machine is likely to crash, so try not to have any other programs open.
# Determine the model name string reported by the CPU, e.g., via the "<tt>Model name</tt>" line in {{path|/proc/cpuinfo}}, and likewise the <tt>cpu_family</tt>, <tt>model</tt> and <tt>stepping</tt>.
# Grab a copy of the example patch below and update it to reflect the parameters, frequencies and voltages you found.
# Apply the patch to your kernel (tested with 2.6.13.1 and 2.6.14-rc2).
# To prevent the ACPI table from overriding your table, disable the <tt>CONFIG_X86_SPEEDSTEP_CENTRINO_ACPI</tt> kernel option.
# Compile and install the new kernel.

The changes should be active now. If you want to see debug information attesting to thus, do the following:

# Reboot in <tt>single</tt> mode.
# {{cmdroot|echo 2 > /sys/module/cpufreq/parameters/debug}}
# {{cmdroot|modprobe speedstep-centrino}}
# {{cmdroot|dmesg}} and check for the message "<tt>speedstep-centrino: found "Intel(R) Pentium(R) M processor </tt>..."

If you don't see that message, you got the <tt>cpu_id</tt> or <tt>model_name</tt> parmaeters wrong. If your system crashes, re-test the voltages and adjust accordingly.

Please report your results (including voltages)!

=== Linux kernel patch (example) ===

The following example shows how to undervolt a Pentium M 750 (1.86GHz) on a ThinkPad {{T43}}. As discussed above, the parameters are specific to this one CPU. You will need to experimentally find the correct settings for your own CPU and adjust the patch accordingly.

Note that the Pentium M 750 has a 533MHz FSB (quad-pumped 133MHz), hence the use of <tt>OP133</tt>. If you have a Pentium M with 400MHz FSB (i.e., quad-pumped 100MHz, found in [[Intel Pentium M (Banias)|Banias]] and older [[Intel Pentium M (Dothan)|Dothan]]) then in the voltage table change <tt>OP133</tt> to <tt>OP</tt>.

{{CodeRef|undervolt-pentium-m-2.6.13.1.patch}}

Don't forget to disable <tt>CONFIG_X86_SPEEDSTEP_CENTRINO_ACPI</tt>.

==Alternative 2: patch with user-space control==

{{NOTE|There's a new project under http://linux-phc.sourceforge.net/ with updated patches. Note that the list of voltages may be reversed (lowest frequency first) compared to the original patch disucssed here. }}

If you want to use the Ubuntu 2.6.15 Kernel, please have a look at this thread: http://ubuntuforums.org/showthread.php?t=146366

The [http://fabrice.bellamy.club.fr/bdz.undervolt.2005.10.22.a.patch bdz.undervolt.2005.10.22.a.patch] patch, written by Gentoo-Wiki user "Bdz", allows voltages to be changed without reboot.

It presents a userspace interface, as in the following example:
:{{cmdroot|cat /sys/devices/system/cpu/cpu0/cpufreq/voltage_table}}
:{{cmdresult|1356,1356,1356,1356,1356,1356,1356,1244,1116,988}}
:{{cmdroot|echo "1084,1084,1084,1084,1084,1084,1084,988,908,860" >/sys/devices/system/cpu/cpu0/cpufreq/voltage_table}}

The relevant [http://gentoo-wiki.com/HOWTO_Undervolt_a_Pentium_M_CPU page] on Gentoo-Wiki providues further information and some helpful hints and scripts for voltage adjustment.

When applying this patch be sure to keep the "ACPI tables for decoding frequency pairs" option -- this patch only allows adjustment of the voltages for the normal clock speeds as reported by the ACPI table in the BIOS. On some models (e.g., ThinkPad {{T43}}) this does not include all clock speeds supported by the processor.

===Initscript===
This is a Gentoo initscript for the patch from Gentoo-Wiki user "Bdz".

Configuration file
<pre>
# /etc/conf.d/undervoltage

# voltage table sysfs interface
VTABLE_SYSFS="/sys/devices/system/cpu/cpu0/cpufreq/voltage_table"

# switch back to DEFAULT_VTABLE if undervoltage is stopped? [yes/no]
SWITCH_BACK="no"

# pentium-m banias 1,7GHz default voltages
DEFAULT_VTABLE="1484,1308,1228,1116,1004,956"
# pentium-m banias 1,7GHz lowered voltages [ -208mV ]
MOD_VTABLE="1276,1100,1020,908,796,748"
</pre>

Initscript
<pre>
#!/sbin/runscript
# Copyright 1999-2005 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Header: $

sysfs_check() {

if ! [ -e ${VTABLE_SYSFS} ]; then
logger "No sysfs voltage_table present. Modifying vcore voltage failed."
eerror "It seems that the undervolting patch has not been applied to the kernel."
eerror "see http://gentoo-wiki.com/HOWTO_Undervolt_a_Pentium_M_CPU for further information"
return 1
fi
}

start() {
sysfs_check || return 1
ebegin "Switching to modified voltage table [${MOD_VTABLE}]"
echo ${MOD_VTABLE} > ${VTABLE_SYSFS}
eend $?
}

# I think it is not necessary to switch to the default voltage table on shutdown
stop() {
if [ $SWITCH_BACK = "yes" ]; then
ebegin "Switching back to default voltage table [${DEFAULT_VTABLE}]"
echo ${DEFAULT_VTABLE} > ${VTABLE_SYSFS}
eend $?
fi
}
</pre>

==Alternative 3: another patch with user-space control==

The [http://avkrok.net/nw8240/centrino-voltages.diff centrino-voltages.diff] patch, written by Rickard Holmberg, also provides user-space control. See [http://avkrok.net/nw8240/ here] and [http://mailman.linux-thinkpad.org/pipermail/linux-thinkpad/2005-December/030772.html here] for usage.

==Stress Testing==

This [[Undervolt Stress Testing Script|script]] illustrates a very conservative method to stress test your lowered voltage settings.

==Tested frequencies==

If you have done excessive testing with user defined frequencies (stable system for over a month).
and no lookups occur when computing primes with mprime http://mersenne.org/ (gentoo: 'emerge gimps')
you can post your frequencies here. But note that this is just a rough indication, since the stable values will differ between individual processors, even in the same model.

{| border="1" cellpadding="2" cellspacing="0"
! CPU Type !! GHz !! Frequency Steps
|-
| Pentium-M Banias || 1.7 || 1276,1100,1020,908,796,748
|-
| Pentium-M Dothan || 1.4 || 924,892,860,828,796,764,732,700
|-
| Pentium-M Dothan || 1.86 || 1068,972,876,780,700
|-
| Pentium-M SL6F7 || 1.6 || 1196,1052,956,860,780,732
|}

[[Category:Patches]]

Pentium M undervolting and underclocking

2006-09-04T05:48:32Z

Gravix: cleaned up some grammar and added a personal experience with undervolting success

== Background ==

Intel Pentium M processors from the [[Intel Pentium M (Dothan)|Dothan]] and [[Intel Pentium M (Banias)|Banias]] families can be instructed to operate at voltage and clock frequencies lower than the nominal ones recommended by Intel and used by ThinkPads by default. Experience shows that the processor may continue working correctly at lower-than-nominal voltages and frequencies, thereby reducing power consumption, heat and fan noise.

In the Pentium M, speed and voltage are controlled by software (through the MSR registers). It is up to the operating system to choose the right voltage for each frequency. Normally this is done according to tables published by Intel or according to ACPI tables. However, this can be overriden - in the case of Linux, by a kernel patch.

{{WARN|Following this instructions will operate your CPU under conditions it was not designed for. Even if your system seems stable, it may still suffer transient faults leading to arbitrary data corruption. In addition, errors in following these instructions (or changes between processor models) may operate the CPU ''above'' its nominal parameters, which, if taken too far, can cause kernel panics or even possibly hardware damage}}

For an example of what may be achieved, consider these examples: when voltages on one ThinkPad {{T43}} were reduced by 20-30%, stable CPU temperature dropped by 7-10deg under both idle and burn-in conditions. Combined with [[how to control fan speed|fan speed control]], this greatly reduced the [[Problem with fan noise|problem with fan noise]]. On one user's ThinkPad {{R51}}, an undervolt brought the full-load processor temperature down from 87 degrees to 63 degrees while maintaining full stability. The effect was, however, negligible at idle.

{{NOTE|While under''volting'' has a clear measurable effect, it's not clear if under''clocking'' really works. <tt>/proc/cpuinfo</tt> reflects the underclocked frequency, but enabling debug output on <tt>cpufreq</tt> causes it to say things like "<tt>CPU frequency out of sync: cpufreq and timing core thinks of 533000, is 800000 kHz.</tt>" where the former is the chosen underclocked frequency and the latter is the documented minimum frequency. This discrepancy also causes [[Software Suspend 2]] to oops during suspend.}}

There are several methods to control CPU voltage in Linux, and currently all of them require a patched kernel.

== Alternative 1: patch with hard-coded voltages ==
=== Instructions ===

# Determine the stable voltages for each frequency, using some overclocking/undervolting utility that has specific support for Pentium M ("Centrino") processors. It seems that no such utility exists for Linux. For windows, one good choice is [http://www.pbus-167.com/chc.htm Notebook Hardware Control (NHC)], which conveniently also includes a table of nominal frequencies and voltags (in its help file). Ascertain that at the undervolted settings the CPU actually performs correct computation ([http://www.mersenne.org/freesoft.htm Prime95] in "Tortute Test" mode seems to be a good partial test emphasizing FPU and memory access). Note that beside reducing voltages (undervolting), you can also try to add lower frequencies (underclocking).
# Determine the model name string reported by the CPU, e.g., via the "<tt>Model name</tt>" line in {{path|/proc/cpuinfo}}, and likewise the <tt>cpu_family</tt>, <tt>model</tt> and <tt>stepping</tt>.
# Grab a copy of the example patch below and update it to reflect the parameters, frequencies and voltages you found.
# Apply the patch to your kernel (tested with 2.6.13.1 and 2.6.14-rc2).
# To prevent the ACPI table from overriding your table, disable the <tt>CONFIG_X86_SPEEDSTEP_CENTRINO_ACPI</tt> kernel option.
# Compile and install the new kernel.

The changes should be active now. If you want to see debug information attesting to thus, do the following:

# Reboot in <tt>single</tt> mode.
# {{cmdroot|echo 2 > /sys/module/cpufreq/parameters/debug}}
# {{cmdroot|modprobe speedstep-centrino}}
# {{cmdroot|dmesg}} and check for the message "<tt>speedstep-centrino: found "Intel(R) Pentium(R) M processor </tt>..."

If you don't see that message, you got the <tt>cpu_id</tt> or <tt>model_name</tt> parmaeters wrong. If your system crashes, re-test the voltages and adjust accordingly.

Please report your results (including voltages)!

=== Linux kernel patch (example) ===

The following example shows how to undervolt a Pentium M 750 (1.86GHz) on a ThinkPad {{T43}}. As discussed above, the parameters are specific to this one CPU. You will need to experimentally find the correct settings for your own CPU and adjust the patch accordingly.

Note that the Pentium M 750 has a 533MHz FSB (quad-pumped 133MHz), hence the use of <tt>OP133</tt>. If you have a Pentium M with 400MHz FSB (i.e., quad-pumped 100MHz, found in [[Intel Pentium M (Banias)|Banias]] and older [[Intel Pentium M (Dothan)|Dothan]]) then in the voltage table change <tt>OP133</tt> to <tt>OP</tt>.

{{CodeRef|undervolt-pentium-m-2.6.13.1.patch}}

Don't forget to disable <tt>CONFIG_X86_SPEEDSTEP_CENTRINO_ACPI</tt>.

==Alternative 2: patch with user-space control==

{{NOTE|There's a new project under http://linux-phc.sourceforge.net/ with updated patches. Note that the list of voltages may be reversed (lowest frequency first) compared to the original patch disucssed here. }}

If you want to use the Ubuntu 2.6.15 Kernel, please have a look at this thread: http://ubuntuforums.org/showthread.php?t=146366

The [http://fabrice.bellamy.club.fr/bdz.undervolt.2005.10.22.a.patch bdz.undervolt.2005.10.22.a.patch] patch, written by Gentoo-Wiki user "Bdz", allows voltages to be changed without reboot.

It presents a userspace interface, as in the following example:
:{{cmdroot|cat /sys/devices/system/cpu/cpu0/cpufreq/voltage_table}}
:{{cmdresult|1356,1356,1356,1356,1356,1356,1356,1244,1116,988}}
:{{cmdroot|echo "1084,1084,1084,1084,1084,1084,1084,988,908,860" >/sys/devices/system/cpu/cpu0/cpufreq/voltage_table}}

The relevant [http://gentoo-wiki.com/HOWTO_Undervolt_a_Pentium_M_CPU page] on Gentoo-Wiki providues further information and some helpful hints and scripts for voltage adjustment.

When applying this patch be sure to keep the "ACPI tables for decoding frequency pairs" option -- this patch only allows adjustment of the voltages for the normal clock speeds as reported by the ACPI table in the BIOS. On some models (e.g., ThinkPad {{T43}}) this does not include all clock speeds supported by the processor.

===Initscript===
This is a Gentoo initscript for the patch from Gentoo-Wiki user "Bdz".

Configuration file
<pre>
# /etc/conf.d/undervoltage

# voltage table sysfs interface
VTABLE_SYSFS="/sys/devices/system/cpu/cpu0/cpufreq/voltage_table"

# switch back to DEFAULT_VTABLE if undervoltage is stopped? [yes/no]
SWITCH_BACK="no"

# pentium-m banias 1,7GHz default voltages
DEFAULT_VTABLE="1484,1308,1228,1116,1004,956"
# pentium-m banias 1,7GHz lowered voltages [ -208mV ]
MOD_VTABLE="1276,1100,1020,908,796,748"
</pre>

Initscript
<pre>
#!/sbin/runscript
# Copyright 1999-2005 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Header: $

sysfs_check() {

if ! [ -e ${VTABLE_SYSFS} ]; then
logger "No sysfs voltage_table present. Modifying vcore voltage failed."
eerror "It seems that the undervolting patch has not been applied to the kernel."
eerror "see http://gentoo-wiki.com/HOWTO_Undervolt_a_Pentium_M_CPU for further information"
return 1
fi
}

start() {
sysfs_check || return 1
ebegin "Switching to modified voltage table [${MOD_VTABLE}]"
echo ${MOD_VTABLE} > ${VTABLE_SYSFS}
eend $?
}

# I think it is not necessary to switch to the default voltage table on shutdown
stop() {
if [ $SWITCH_BACK = "yes" ]; then
ebegin "Switching back to default voltage table [${DEFAULT_VTABLE}]"
echo ${DEFAULT_VTABLE} > ${VTABLE_SYSFS}
eend $?
fi
}
</pre>

==Alternative 3: another patch with user-space control==

The [http://avkrok.net/nw8240/centrino-voltages.diff centrino-voltages.diff] patch, written by Rickard Holmberg, also provides user-space control. See [http://avkrok.net/nw8240/ here] and [http://mailman.linux-thinkpad.org/pipermail/linux-thinkpad/2005-December/030772.html here] for usage.

==Stress Testing==

This [[Undervolt Stress Testing Script|script]] illustrates a very conservative method to stress test your lowered voltage settings.

==Tested frequencies==

If you have done excessive testing with user defined frequencies (stable system for over a month).
and no lookups occur when computing primes with mprime http://mersenne.org/ (gentoo: 'emerge gimps')
you can post your frequencies here. But note that this is just a rough indication, since the stable values will differ between individual processors, even in the same model.

{| border="1" cellpadding="2" cellspacing="0"
! CPU Type !! GHz !! Frequency Steps
|-
| Pentium-M Banias || 1.7 || 1276,1100,1020,908,796,748
|-
| Pentium-M Dothan || 1.4 || 924,892,860,828,796,764,732,700
|-
| Pentium-M Dothan || 1.86 || 1068,972,876,780,700
|-
| Pentium-M SL6F7 || 1.6 || 1196,1052,956,860,780,732
|}

[[Category:Patches]]

Rovclock

2006-09-03T06:34:32Z

Gravix: /* Minimum stable clockrates */

==General==
Rovclock is a utility to control frequency rates of your Radeon card.

It is very helpful for underclocking the Radeon chip in order to save power when running on batteries. Also, by underclocking it is possible to prevent the fan from running.

It can also be used to gain performance by overclocking.

{{NOTE|While this utility complements the [[How to make use of Graphics Chips Power Management features|DynamicClocks]] option of the X.org <tt>radeon</tt> driver, it is not compatible with the power saving mode of the [[fglrx]] driver. Setting power saving mode using both [[fglrx]] and [[rovclock]] results in an unusably slow desktop.}}

==Features==
Used to under-/overclock Radeon gfx-cards.
* Controls GPU core frequency
* Controls gfx-memory frequency

== Project Homepage / Availability ==
* Homepage: http://www.hasw.net/linux/

==Usage==
*Set the core frequency (-c) to 100 Mhz and the memory frequency (-m) to 120 Mhz.
:{{cmduser|sudo rovclock -c 100 -m 120}}
*Get current frequencies among other information (-i).
:{{cmduser|sudo rovclock -i}}

==Minimum stable clockrates==
* {{A30p}} with Radeon 7000
** LCD: No lower core limit, 90MHz mem (basic use) / 125MHz mem (no artifacts with glxgears)
* {{T42}} with Radeon 7500 NOTE: Setting the memory under 100Mhz may hang your card.
** LCD: 100MHz core, 120MHz memory.
** Using DVI output on Port replicator: 100Mhz core, 180MHz memory.
* {{T42}} with Radeon 9600
** LCD: Core: 54.0 MHz, Mem: 60.75 MHz
* {{T42p}} Firegl T2 (9600), fglrx driver
** 1600x1200 LCD: Core: 81 Mhz, Mem: 67.5 Mhz
* {{T43}} with [[ATI Mobility Radeon X300]]:
** 100MHz core, 120Mz memory (see more [[ATI Mobility Radeon X300|here]])
* {{X31}} with ATI Radeon Mobility M6 LY:
** 90MHz core, 100Mz memory (90/90 is giving distorted picture)
* {{R50p}} with FireGL Mobility T2:
** 1600x1200 LCD: Core: 100 MHz Mem: 120Mz
* {{R51}} with FireGL 9000
** Core: 50 Mhz Mem: 50 Mhz (2d only, lower may be possible, 10mhz definitely doesn't work.)

== See also ==
*[[How to make use of Graphics Chips Power Management features]] using the <tt>DynamicClocks</tt> option of the <tt>radeon</tt> driver
*[http://forums.gentoo.org/viewtopic-t-343029.html Gentoo forum discussion]
*[[Radeontool]]

[[Category:Tools]]