ThinkWiki - User contributions [en]

Pentium M undervolting and underclocking

2006-01-23T23:58:35Z

Rushibhai: /* Background */

== 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, with effects up to and including laptop meltdown.}}

For an example of what may be achieved, on one ThinkPad {{T43}} all voltages could be reduced by 20-30% and moreover, the minimal frequency reduced from 800MHz to 533MHz; this reduced stable CPU temperature 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]].

{{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).<br> 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).<br> 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>.

<pre>--- linux-2.6.13.1-vanilla/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c 2005-09-10 05:42:58.000000000 +0300
+++ linux-2.6.13.1/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c 2005-10-18 04:46:01.000000000 +0200
@@ -54,6 +54,7 @@ enum {
CPU_DOTHAN_A1,
CPU_DOTHAN_A2,
CPU_DOTHAN_B0,
+ CPU_DOTHAN_C0,
CPU_MP4HT_D0,
CPU_MP4HT_E0,
};
@@ -63,6 +64,8 @@ static const struct cpu_id cpu_ids[] = {
[CPU_DOTHAN_A1] = { 6, 13, 1 },
[CPU_DOTHAN_A2] = { 6, 13, 2 },
[CPU_DOTHAN_B0] = { 6, 13, 6 },
+ [CPU_DOTHAN_C0] = { 6, 13, 8 },
[CPU_MP4HT_D0] = {15, 3, 4 },
[CPU_MP4HT_E0] = {15, 4, 1 },
};
@@ -94,6 +97,12 @@ static struct cpufreq_driver centrino_dr
.frequency = (mhz) * 1000, \
.index = (((mhz)/100) << 8) | ((mv - 700) / 16) \
}
+/* Likewise, for processors with 133MHz FSB. */
+#define OP133(mhz, mv) \
+ { \
+ .frequency = (mhz) * 1000, \
+ .index = (((mhz)/133) << 8) | ((mv - 700) / 16) \
+ }

/*
* These voltage tables were derived from the Intel Pentium M
@@ -202,7 +211,26 @@ static struct cpufreq_frequency_table ba
OP(1700, 1484),
{ .frequency = CPUFREQ_TABLE_END }
};
+
+/* Intel Pentium M 750, drastically undervoltaged */
+static struct cpufreq_frequency_table pentium_m_750[] =
+{
+ /* MHz mV */
+ OP133( 800, 700),
+ OP133(1066, 780),
+ OP133(1200, 828),
+ OP133(1333, 876),
+ OP133(1466, 924),
+ OP133(1600, 972),
+ OP133(1733, 1020),
+ OP133(1866, 1068),
+ { .frequency = CPUFREQ_TABLE_END }
+};
+
#undef OP
+#undef OP133

#define _BANIAS(cpuid, max, name) \
{ .cpu_id = cpuid, \
@@ -225,6 +253,12 @@ static struct cpu_model models[] =
BANIAS(1500),
BANIAS(1600),
BANIAS(1700),
+ {
+ .cpu_id = &cpu_ids[CPU_DOTHAN_C0],
+ .model_name = "Intel(R) Pentium(R) M processor 1.86GHz",
+ .max_freq = 1866000,
+ .op_points = pentium_m_750
+ },

/* NULL model_name is a wildcard */
{ &cpu_ids[CPU_DOTHAN_A1], NULL, 0, NULL },

</pre>

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

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

Note that this approach 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>

===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 || 1.86 || 1068,972,876,780,700
|-
| Pentium-M SL6F7 || 1.6 || 1196,1052,956,860,780,732
|}

==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.

==External Sources==

* A [http://forums.anandtech.com/messageview.aspx?catid=51&threadid=1677980 forum discussion] of Pentium M undervolting

[[Category:Patches]]

Category talk:X60

2006-01-22T07:21:53Z

Rushibhai: /* Don't revert! */

<nowiki><rant></nowiki>

The new [http://www.notebookreview.com/assets/8714.jpg key layout] is ''evil''.

For crying out loud, with what kind of accuracy do they think I can place my right pinky, with the view obstructed by my palm? It was bad enough when they put {{ibmkey|Backward|#494949}} and {{ibmkey|Forward|#494949}} in the "vacant" space around {{key|Up}}, so that I keep switching pages in my browser when I try to scroll up. But making the right {{key|Ctrl}} and {{key|Alt}} keys narrower than a finger and penalizing any miss with a focus-grabbing {{key|Menu}} popup? That's insane.

Oh, yes, I'm sure the Pointy Haired purchasers will love it ("ooh, more keys!"). Those Lenovo engineers, they seem to have lost all dignity when they switched employers.

<nowiki></rant></nowiki> --[[User:Thinker|Thinker]] 14:41, 5 Jan 2006 (CET)
----

Holy cow, I totally agree. I never understand decisions like this, for all you have to do is ask some people that *actually use the laptop* every day and they will tell you why this is bad / good. I just placed a micro-rant about the addition of the Windows keys too. Looks like I'll stay with my good old T43p for a while!

-[[User:gsmenden|gsmenden]] 14:41, 5 Jan 2006 (CET)
----
Totally agree, the windows and browser keys are ''evil''.

I was afraid when the Z series where introduced with Windows keys, that other future ThinkPads would also have them, and it seems I was right.

I will be sticking with my current ThinkPad for as long as I can, one can always hope they ''correct'' this problem in later models, but I am not hopeful.

--[[User:Tonko|Tonko]] 18:15, 5 Jan 2006 (CET)
----

== Don't revert! ==

My Edit is based on new information. There *ARE* single core models! Look at the X60/X60s data sheet: http://www5.pc.ibm.com/europe/me.nsf/LenovoDetail?OpenAgent&key=ThinkPad:ThinkPad+X+Series:Data+Sheet:English&&cntry=UK-L

----
Sorry, I disagree.

I do not think those datasheets cannot be trusted, the only source I think that can more or less be trusted is tabook.pdf. Those datasheets contain specs of *possible* configs, configs that might never be released. We have seen that with other machine types where datasheets or HMM's have specifications that never shipped.

I think we should stick with actually released hardware specs.

--[[User:Tonko|Tonko]] 02:53, 15 January 2006 (CET)
----
I agree, Tonko, the feature listing only makes sense if it holds only information of models that actually exist like that by default configuration. So tabook is the most reliable source. However, i discovered that the product overview page in the support area of the lenovo page seems to be updated more frequently than tabook and i would think that it also only lists actually existing configurations.

[[User:Wyrfel|Wyrfel]] 11:59, 15 January 2006 (CET)
----
I have updated the processor types for X60 and X60s as per anandtech CES 2006 report [http://www.anandtech.com/tradeshows/showdoc.aspx?i=2665&p=6 link here].<br>
--[[User:Rushibhai|Rushibhai]] 08:17, 22 January 2006 (CET)

Category talk:X60

2006-01-22T07:17:10Z

Rushibhai: /* Don't revert! */

<nowiki><rant></nowiki>

The new [http://www.notebookreview.com/assets/8714.jpg key layout] is ''evil''.

For crying out loud, with what kind of accuracy do they think I can place my right pinky, with the view obstructed by my palm? It was bad enough when they put {{ibmkey|Backward|#494949}} and {{ibmkey|Forward|#494949}} in the "vacant" space around {{key|Up}}, so that I keep switching pages in my browser when I try to scroll up. But making the right {{key|Ctrl}} and {{key|Alt}} keys narrower than a finger and penalizing any miss with a focus-grabbing {{key|Menu}} popup? That's insane.

Oh, yes, I'm sure the Pointy Haired purchasers will love it ("ooh, more keys!"). Those Lenovo engineers, they seem to have lost all dignity when they switched employers.

<nowiki></rant></nowiki> --[[User:Thinker|Thinker]] 14:41, 5 Jan 2006 (CET)
----

Holy cow, I totally agree. I never understand decisions like this, for all you have to do is ask some people that *actually use the laptop* every day and they will tell you why this is bad / good. I just placed a micro-rant about the addition of the Windows keys too. Looks like I'll stay with my good old T43p for a while!

-[[User:gsmenden|gsmenden]] 14:41, 5 Jan 2006 (CET)
----
Totally agree, the windows and browser keys are ''evil''.

I was afraid when the Z series where introduced with Windows keys, that other future ThinkPads would also have them, and it seems I was right.

I will be sticking with my current ThinkPad for as long as I can, one can always hope they ''correct'' this problem in later models, but I am not hopeful.

--[[User:Tonko|Tonko]] 18:15, 5 Jan 2006 (CET)
----

== Don't revert! ==

My Edit is based on new information. There *ARE* single core models! Look at the X60/X60s data sheet: http://www5.pc.ibm.com/europe/me.nsf/LenovoDetail?OpenAgent&key=ThinkPad:ThinkPad+X+Series:Data+Sheet:English&&cntry=UK-L

----
Sorry, I disagree.

I do not think those datasheets cannot be trusted, the only source I think that can more or less be trusted is tabook.pdf. Those datasheets contain specs of *possible* configs, configs that might never be released. We have seen that with other machine types where datasheets or HMM's have specifications that never shipped.

I think we should stick with actually released hardware specs.

--[[User:Tonko|Tonko]] 02:53, 15 January 2006 (CET)
----
I agree, Tonko, the feature listing only makes sense if it holds only information of models that actually exist like that by default configuration. So tabook is the most reliable source. However, i discovered that the product overview page in the support area of the lenovo page seems to be updated more frequently than tabook and i would think that it also only lists actually existing configurations.

[[User:Wyrfel|Wyrfel]] 11:59, 15 January 2006 (CET)
----
I have updated the processor types for X60 and X60s as per anandtech CES 2006 report.<br>
--[[User:Rushibhai|Rushibhai]] 08:17, 22 January 2006 (CET)

Category:X60

2006-01-22T07:09:48Z

Rushibhai: /* ThinkPad X60 */

{| width="100%"
|style="vertical-align:top" |
<div style="margin: 0; margin-right:10px; border: 1px solid #dfdfdf; padding: 0em 1em 1em 1em; background-color:#F8F8FF; align:right;">
=== ThinkPad X60 ===
This pages gives an overview of all ThinkPad X60 related topics.

* [[Intel Core Duo (Yonah)]] CPU with 1.83 or 1.66 GHz (standard voltage) in X60, or [[Intel Core Solo (Yonah)]] with 1.66 GHz in X60s
* [[Intel Graphics Media Accelerator 950]]
** 12.1" TFT display with 1024x768 resolution
* 512 MB [[PC2-5300]] memory standard
* 40, 60, 80, 100 GB 5400 rpm or 100 GB 7200 rpm SATA 2.5" HDD
** [[Active Protection System|IBM Active Protection System]]
* [[AD1981HD]] AC'97 Audio controller
* [[Ethernet Controllers# Intel Gigabit (10/100/1000)|Intel Gigabit Ethernet Controller]]
* [[MiniPCI Express slot]] with one of the following:
** [[Intel PRO/Wireless 3945ABG Mini-PCI Express Adapter]]
* [[Embedded Security Subsystem|IBM Embedded Security Subsystem 2.0]]
* [[Integrated Fingerprint Reader]]
* [[SD Card slot]] with IO support
* [[CardBus slot]] (Type 2)
* Firewire (IEEE1394)
</div>
|style="vertical-align:top" |
[[Image:ThinkPadX60.jpg|ThinkPad X60]]
|}

==== Reviews ====
* [http://www.notebookreview.com/default.asp?newsID=2701 NotebookReview.com], 2006-01-05

[[Category:Models]]