What about the GPUs?

[whxvd]

As far as I understand, mbpfan reads temperature values only from the coretemp module. That does not inlude the temperature of the discrete GPU. As far as I know, GPUs can become very (too) hot, too. Is it for some reason known, that that can never be a problem on Macbook Pros?

[gaul]

Pull requests welcome.

[leukimi]

iMac mid 2007 with ATI Radeon RV630/M76 [Mobility Radeon HD 2600 XT/2700] with 2+1=3GB RAM

Adding a request to incorporate GPU temperature reading into mbpfan.

Why GPU temperature reading is necessary

The HDD fan seems to have a cooling effect on the GPU when running at 4400 rpm. Opening up the case and removing as much dust as possible seems to help the cooling, but GPU still overheats quickly.

To read the temperature with bash:

sensors -A radeon-pci-0100 | grep temp1 | cut -d ':' -f 2 | cut -d '(' -f 1

LC_ALL=C sensors radeon-pci-0100 -u | grep temp1_input | awk '{printf("%d\n",$2 + 0.5)}

I could not yet figure out how to scan the GPU temperature in mbpfan.c but it is much needed to be able to control the HDD fan directly by reading the radeon GPU. A current workaround is to make all fans speed up at CPU temperature +34°C. As you may guess, the iMac sounds like a departing jet aircraft which is quite tiring after a while.

The GPU-temperature typically reaches +108°C in short time and shuts down the graphical part, making it necessary to speed up HDD fan even before attempting to install any linux system.

To keep the GPU operable, I share config file /etc/mbpfan.conf that typically keeps the GPU between +97°C to +100°C . If the HDD fan does not spin up, the GPU temperature will slowly creep up until the display goes dark. The fans typically run as:

ODD fan: 4126 rpm
HDD fan: 4389 rpm (has the biggest cooling effect on GPU)
CPU fan: 2650 rpm

$ cat /etc/mbpfan.conf 
[general]
# This configuration keeps GPU temperature around 100 degrees Celsius
# CPU temperature is typically 34 degrees Celsius
# ODD fan
min_fan1_speed = 3500
# HDD fan. Small fan to the right bottom. Has biggest cooling effect on GPU.
min_fan2_speed = 2000
# CPU fan. The biggest fan to the left bottom.
min_fan3_speed = 1200

max_fan1_speed = 4400
max_fan2_speed = 5500
max_fan3_speed = 3300

# temperature units in Celsius
low_temp = 29			# if temperature is below this, fans will run at minimum speed
high_temp =30			# if temperature is above this, fan speed will gradually increase
max_temp = 40			# if temperature is above this, fans will run at maximum speed
polling_interval = 1	        # default is 1 seconds

Since iMac mid 2007 can have low RAM, it does run well with linux distributions like antiX linux, Archlinux, Manjaro, Xubuntu and Lubuntu.

Here are some ~/.conkyrc lines that can help to monitor the speeds of the fans on antiX linux, which after testing seems to be the operating system that makes this particular iMac with 3GB RAM the quickest. Probably Archlinux tailored to needs might be even better but requires more manual work to set up.

$ cat $HOME/.conkyrc
...more lines above...
ODD fan:${alignr} ${platform applesmc.768 fan 1} rpm
HDD fan:${alignr} ${platform applesmc.768 fan 2} rpm
CPU fan:${alignr} ${platform applesmc.768 fan 3} rpm
CPU1:${alignr}${cpu cpu1}% ${hwmon 1 temp 2}°C
CPU2:${alignr}${cpu cpu2}% ${hwmon 1 temp 3}°C
GPU:$alignr${hwmon 0 temp 1}°C

[SammyCola]

Glancing at src/mbpfan.c it looks like on line 127 it's directly probing one of the temp inputs.

char *path = smprintf("/sys/devices/platform/coretemp.0/hwmon/hwmon%d/temp%d_input", counter, temp);

Couldn't we probe potential GPU paths and add it to the list of temps it's tracking? The only device I have mbpfan running on is a 2013 Mac Pro (Debian 13), but it looks like the two GPUs would be listed under this path.

# cat /sys/class/drm/card*/device/hwmon/hwmon*/temp*_input 
53000
51000

# sensors radeon-pci-*
radeon-pci-0600
Adapter: PCI adapter
temp1:        +53.0°C  (crit = +120.0°C, hyst = +90.0°C)
pwm1:             30%
freq1:        300 MHz 

radeon-pci-0200
Adapter: PCI adapter
temp1:        +51.0°C  (crit = +120.0°C, hyst = +90.0°C)
pwm1:             30%
freq1:        300 MHz

[gaul]

I don't believe that is_modern_sensors_path (line 127) is meaningful since this is just looking to see what style of path hwmon is using. Rather I believe that additional sensors could be added in retrieve_sensors. I no longer have a MacBook running Linux so this will require some other contributor to test both on hardware with and without GPUs. I do believe that this is an easy fix if you want to try yourself.