High CPU consumption when using psutil.sensors_fans()

[nicolargo]

Hi @giampaolo ,

in Glances, if i enable the fans sensors plugin, i have an huge CPU consumption.

I reproduce the issue with this short code:

import time
import psutil
while True:
    print(psutil.sensors_fans())
    time.sleep(3)

The CPU consumption is the following (~ 14%):

Can you reproduce on your system ?

PsUtil: 5.4.2
OS: Ubuntu 16.04
Hardware: Dell XPS 13

[giampaolo]

Can't reproduce it from here.

import time
import psutil

p = psutil.Process()
while True:
    print(psutil.sensors_fans())
    time.sleep(1)
    print(p.cpu_percent(interval=None))

Output:

{'asus': [sfan(label='cpu_fan', current=2900)]}
0.0
{'asus': [sfan(label='cpu_fan', current=2900)]}
1.0
{'asus': [sfan(label='cpu_fan', current=2900)]}
0.0
{'asus': [sfan(label='cpu_fan', current=2800)]}
1.0
{'asus': [sfan(label='cpu_fan', current=2800)]}
1.0
{'asus': [sfan(label='cpu_fan', current=2800)]}
0.0
{'asus': [sfan(label='cpu_fan', current=2800)]}
0.0
{'asus': [sfan(label='cpu_fan', current=2700)]}
1.0
{'asus': [sfan(label='cpu_fan', current=2700)]}
0.0
{'asus': [sfan(label='cpu_fan', current=2700)]}
0.0

[nicolargo]

Same test on my system:

In [1]: import time
   ...: import psutil
   ...: 
   ...: p = psutil.Process()
   ...: while True:
   ...:     print(psutil.sensors_fans())
   ...:     time.sleep(1)
   ...:     print(p.cpu_percent(interval=None))
   ...:     
{'dell_smm': [sfan(label='Processor Fan', current=0)]}
0.0
{'dell_smm': [sfan(label='Processor Fan', current=0)]}
33.3
{'dell_smm': [sfan(label='Processor Fan', current=0)]}
33.9
{'dell_smm': [sfan(label='Processor Fan', current=0)]}
33.3
{'dell_smm': [sfan(label='Processor Fan', current=0)]}
33.3
{'dell_smm': [sfan(label='Processor Fan', current=0)]}
33.3
{'dell_smm': [sfan(label='Processor Fan', current=0)]}
33.3
{'dell_smm': [sfan(label='Processor Fan', current=0)]}
33.2
{'dell_smm': [sfan(label='Processor Fan', current=0)]}
33.8
{'dell_smm': [sfan(label='Processor Fan', current=0)]}
33.3
{'dell_smm': [sfan(label='Processor Fan', current=0)]}
33.9

[nicolargo]

Just have a look and i can also reproduce the issue with a simple command line:

watch cat /sys/class/hwmon/hwmon2/fan1_input

So not a PsUtil issue but a Ubuntu/Dell Sensors one...

[wordlessly]

Same output on my system. CPU usage does not go up. Am I missing the fan speed sensor?

{}
0.0
{}
0.0
{}
0.0
{}
0.0