CPU temp and scaling in Linux

To see your processor temperature in linux, you need the lm-sensor package:

apt-get install lm-sensors

Then you need to setup the sensors specific to your machine:

sensors-detect

It scans your system, accepting the default is pretty safe. Follow instructions at the end to load the required modules for your sensors

benedict@benedict-laptop:~$ sudo sensors-detect
# sensors-detect revision 5818 (2010-01-18 17:22:07 +0100)
# System: Dell Inc. Inspiron 910

This program will help you determine which kernel modules you need
to load to use lm_sensors most effectively. It is generally safe
and recommended to accept the default answers to all questions,
unless you know what you're doing.

Some south bridges, CPUs or memory controllers contain embedded sensors.
Do you want to scan for them? This is totally safe. (YES/no):
Silicon Integrated Systems SIS5595... No
VIA VT82C686 Integrated Sensors... No
VIA VT8231 Integrated Sensors... No
AMD K8 thermal sensors... No
AMD Family 10h thermal sensors... No
AMD Family 11h thermal sensors... No
Intel Core family thermal sensor... No
Intel Atom thermal sensor... Success!
(driver `coretemp')
Intel AMB FB-DIMM thermal sensor... No
VIA C7 thermal sensor... No
VIA Nano thermal sensor... No

Some Super I/O chips contain embedded sensors. We have to write to
standard I/O ports to probe them. This is usually safe.
Do you want to scan for Super I/O sensors? (YES/no):
Probing for Super-I/O at 0x2e/0x2f
Trying family `National Semiconductor'... No
Trying family `SMSC'... No
Trying family `VIA/Winbond/Nuvoton/Fintek'... No
Trying family `ITE'... No
Probing for Super-I/O at 0x4e/0x4f
Trying family `National Semiconductor'... No
Trying family `SMSC'... No
Trying family `VIA/Winbond/Nuvoton/Fintek'... No
Trying family `ITE'... No

Some systems (mainly servers) implement IPMI, a set of common interfaces
through which system health data may be retrieved, amongst other things.
We first try to get the information from SMBIOS. If we don't find it
there, we have to read from arbitrary I/O ports to probe for such
interfaces. This is normally safe. Do you want to scan for IPMI
interfaces? (YES/no):
Probing for `IPMI BMC KCS' at 0xca0... No
Probing for `IPMI BMC SMIC' at 0xca8... No

Some hardware monitoring chips are accessible through the ISA I/O ports.
We have to write to arbitrary I/O ports to probe them. This is usually
safe though. Yes, you do have ISA I/O ports even if you do not have any
ISA slots! Do you want to scan the ISA I/O ports? (YES/no):
Probing for `National Semiconductor LM78' at 0x290... No
Probing for `National Semiconductor LM79' at 0x290... No
Probing for `Winbond W83781D' at 0x290... No
Probing for `Winbond W83782D' at 0x290... No

Lastly, we can probe the I2C/SMBus adapters for connected hardware
monitoring devices. This is the most risky part, and while it works
reasonably well on most systems, it has been reported to cause trouble
on some systems.
Do you want to probe the I2C/SMBus adapters now? (YES/no):
Using driver `i2c-i801' for device 0000:00:1f.3: Intel 82801G ICH7
Module i2c-i801 loaded successfully.
Module i2c-dev loaded successfully.

Next adapter: intel drm CRTDDC_A (i2c-0)
Do you want to scan it? (YES/no/selectively):

Next adapter: intel drm LVDSDDC_C (i2c-1)
Do you want to scan it? (YES/no/selectively):
Client found at address 0x50
Probing for `Analog Devices ADM1033'... No
Probing for `Analog Devices ADM1034'... No
Probing for `SPD EEPROM'... No
Probing for `EDID EEPROM'... Yes
(confidence 8, not a hardware monitoring chip)

Now follows a summary of the probes I have just done.
Just press ENTER to continue:

Driver `coretemp':
* Chip `Intel Atom thermal sensor' (confidence: 9)

To load everything that is needed, add this to /etc/modules:
#----cut here----
# Chip drivers
coretemp
#----cut here----
If you have some drivers built into your kernel, the list above will
contain too many modules. Skip the appropriate ones!

Do you want to add these lines automatically to /etc/modules? (yes/NO)yes
Successful!

Monitoring programs won't work until the needed modules are
loaded. You may want to run '/etc/init.d/module-init-tools start'
to load them.

Unloading i2c-dev... OK
Unloading i2c-i801... OK


Then run 'sensors':

benedict@benedict-laptop:~$ sensors
acpitz-virtual-0
Adapter: Virtual device
temp1: +58.0°C (crit = +102.0°C)

coretemp-isa-0000
Adapter: ISA adapter
Core 0: +40.0°C (crit = +90.0°C)

coretemp-isa-0001
Adapter: ISA adapter
Core 1: +40.0°C (crit = +90.0°C)


Chances are, your linux distro are already doing frequency scaling, you just want to see how its doing. You need the cpufrequtils package.

Then run cpufreq-info to view the current freq and other relevant info:


benedict@benedict-laptop:~$ cpufreq-info
cpufrequtils 006: cpufreq-info (C) Dominik Brodowski 2004-2009
Report errors and bugs to cpufreq@vger.kernel.org, please.
analyzing CPU 0:
driver: acpi-cpufreq
CPUs which run at the same hardware frequency: 0 1
CPUs which need to have their frequency coordinated by software: 0
maximum transition latency: 10.0 us.
hardware limits: 800 MHz - 1.60 GHz
available frequency steps: 1.60 GHz, 1.33 GHz, 1.07 GHz, 800 MHz
available cpufreq governors: conservative, ondemand, userspace, powersave, performance
current policy: frequency should be within 800 MHz and 1.60 GHz.
The governor "ondemand" may decide which speed to use
within this range.
current CPU frequency is 800 MHz.
cpufreq stats: 1.60 GHz:18.06%, 1.33 GHz:0.81%, 1.07 GHz:1.00%, 800 MHz:80.12% (2083337)
analyzing CPU 1:
driver: acpi-cpufreq
CPUs which run at the same hardware frequency: 0 1
CPUs which need to have their frequency coordinated by software: 1
maximum transition latency: 10.0 us.
hardware limits: 800 MHz - 1.60 GHz
available frequency steps: 1.60 GHz, 1.33 GHz, 1.07 GHz, 800 MHz
available cpufreq governors: conservative, ondemand, userspace, powersave, performance
current policy: frequency should be within 800 MHz and 1.60 GHz.
The governor "ondemand" may decide which speed to use
within this range.
current CPU frequency is 1.60 GHz.
cpufreq stats: 1.60 GHz:2.42%, 1.33 GHz:0.12%, 1.07 GHz:0.12%, 800 MHz:97.33% (139908)


That's all!

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