Russell Coker <russell@coker.com.au> writes:
I think that all systems I run only use PCIe cards for video.
At least one generation of intel boards used PCIe as the backplane. Newer ones use quickpath, IIRC. Older ones used PCI. In other words, if you have disks plugged into the southbridge, they could well be using PCIe even though they're not plugged into a user-pluggable PCIe slot. Likewise for onboard NICs, etc.
The "lspci" command indicates that the "PCI" bus is used for bridging to USB, for on-board video, and for on-board Ethernet. Would that bus be PCI or PCIe?
I don't know a way to tell PCI from PCIe on a running system. Your best bet is probably to look up what the northbridge chipset is, then ask Wikipedia what backplane that northbridge typically shipped with.
I was reading the above blog post about reducing power use and it mentioned the pcie_aspm=force kernel option. I had previously used that option on a Thinkpad which was defective in some way related to CPU power use and had assumed that the option was only for defective systems, but maybe it can also be used productively on systems that aren't broken.
Would it be worth adding to other systems?
I vaguely remember using it on me Eee PC 1008 as part of a general power-saving cleanup, but I don't remember if I ever measured any benefit from that specific option. Possibly powertop suggested it.