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111 lines
4.0 KiB
Groff
111 lines
4.0 KiB
Groff
.TH FANCONTROL 8 "June 2007" "lm-sensors 3"
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.SH NAME
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fancontrol \- automated software based fan speed regulation
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.SH SYNOPSIS
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.B fancontrol
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.I [configfile]
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.SH DESCRIPTION
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\fBfancontrol\fP is a shell script for use with lm_sensors. It reads its
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configuration from a file, then calculates fan speeds from temperatures and
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sets the corresponding PWM outputs to the computed values.
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.SH WARNING
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Please be careful when using the fan control features of your mainboard, in
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addition to the risk of burning your CPU, at higher temperatures there will be
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a higher wearout of your other hardware components, too. So if you plan to use
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these components in 50 years, \fBmaybe\fP you shouldn't use fancontrol
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at all. Also please keep in mind most fans aren't designed to be
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powered by a PWMed voltage.
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In practice it doesn't seem to be a major issue, the fans will get slightly
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warmer, just be sure to have a temperature alarm and/or shutdown call, in case
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some fan fails, because you probably won't hear it anymore ;)
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.SH CONFIGURATION
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For easy configuration, there's a script
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named \fBpwmconfig\fP(8) which lets you interactively write your
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configuration file for \fBfancontrol\fP. Alternatively you can write this
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file yourself using the information from this manpage.
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Since most of you are going to use \fBpwmconfig\fP(8) script, the config
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file syntax will be discussed last. First I'm going to describe the various
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variables available for changing \fBfancontrol\fP's behaviour:
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.TP
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.B INTERVAL
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This variable defines at which interval in seconds the main loop of
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\fBfancontrol\fP will be executed
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.TP
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.B FCTEMPS
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Maps PWM outputs to temperature sensors so \fBfancontrol\fP knows which
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temperature sensors should be used for calculation of new values for
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the corresponding PWM outputs.
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.TP
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.B FCFANS
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FCFANS records the association between a PWM and a fan.
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Then \fBfancontrol\fP can check the fan speed and restart it if it
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stops unexpectedly.
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.TP
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.B MINTEMP
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The temperature below which the fan gets switched to minimum speed.
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.TP
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.B MAXTEMP
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The temperature over which the fan gets switched to maximum speed.
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.TP
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.B MINSTART
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Sets the minimum speed at which the fan begins spinning. You should
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use a safe value to be sure it works, even when the fan gets old.
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.TP
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.B MINSTOP
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The minimum speed at which the fan still spins. Use a safe value here,
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too.
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.TP
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.B MINPWM
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The PWM value to use when the temperature is below MINTEMP.
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Typically, this will be either 0 if it is OK for the fan to plain
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stop, or the same value as MINSTOP if you don't want the fan to
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ever stop.
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If this value isn't defined, it defaults to 0 (stopped fan).
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.TP
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.B MAXPWM
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The PWM value to use when the temperature is over MAXTEMP.
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If this value isn't defined, it defaults to 255 (full speed).
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.PP
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The configuration file format is a bit strange:
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.IP
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.nf
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VARIABLE=chip/pwmdev=value chip/pwmdev2=value2
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VARIABLE2=...
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.fi
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.PP
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Each variable has its own line. The variable name is followed by an equal sign
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and the device=value pairs. These consist of the relative path to the pwm
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output (from /proc/sys/dev/sensors, /sys/bus/i2c/devices or /sys/class/hwmon
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depending on the kernel version) for which the value is valid, equal sign
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followed by the value and are separated by a blank. Example:
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.IP
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MINTEMP=w83627hf-isa-0290/pwm2=40 w83627hf-isa-0290/pwm1=54
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.PP
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You have to play with the temperature values a bit to get happy. For initial
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setup I recommend using the \fBpwmconfig\fP script. Small changes can be made by
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editing the config file directly following the rules above.
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.SH THE ALGORITHM
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\fBfancontrol\fP first reads its configuration, writes it to arrays and loops its
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main function. This function gets the temperatures and fanspeeds from
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kernel driver files and calculates new speeds depending on temperature
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changes, but only if the temp is between MINTEMP and MAXTEMP. After that, the
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new values are written to the PWM outputs. Currently the speed increases
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quadratically with rising temperature. This way you won't hear your fans most
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of the time at best.
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.SH SEE ALSO
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pwmconfig(8), sensors(1).
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.SH AUTHOR
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.PP
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Marius Reiner <marius.reiner@hdev.de>
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