0

Recently I had a problem with the fan working all the time.

Someone suggested to use powertop --auto-tune or to write auto into /sys/bus/pci/devices/0000\:01\:00.0/power/control

My question is:

What is /sys/bus/pci/devices/0000\:01\:00.0 ? - I guess it points to some device (probably my NVIDIA graphic controller). How do I know which device is which? What is meant by 0000 and :01 and :00.0? - Where can I find an explanation for how the devices are written?

Nmath
  • 12,664
aviv
  • 158

1 Answers1

2

/sys/bus/pci/devices/0000:01:00.0/power/control

  • sys is a virtual filesytem that allows you to get information about the system and its components in a structured way.

  • /sys/bus/ This directory contains one subdirectory for each of the bus types in the kernel. Inside each of these directories are two subdirectories:

           devices
              This subdirectory contains symbolic links to
              entries in /sys/devices that correspond to the
              devices discovered on this bus.

       drivers
          This subdirectory contains one subdirectory for
          each device driver that is loaded on this bus.

The 0000:01:00.0:

  • "0000" is the PCI domain
  • "01" points to the PCI bus number in that domain
  • "00" is the device number
  • "0" is the function in the device

Often you see it described like this: /sys/bus/pci/devices/<Domain>:<Bus>:<Device>.<Function>/power/control

  • power/controle is used to manipulate runtime power management.

nvidia has a large manual on this. Chapter 22 is about this function.

Rinzwind
  • 309,379