On Fri, May 17, 2013 at 7:20 PM, Phillip Susi <psusi@xxxxxxxxxx> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 05/17/2013 08:40 PM, Bjorn Helgaas wrote: >> Right; I meant RO per the PCIe spec. If it's RW on your chip, >> setpci should be able to write it. > > I assume it would do no good to change it at this point; it would need > to already be set at the time the kernel reads it and decides whether > or not to enable it, so I'd have to have grub set it before loading > the kernel. Yeah, setting the capability bits after the kernel has booted wouldn't change anything except what lspci reports. >> If you can measure the power consumption, you might be able to see >> a difference there. I've seen people report that, but don't know >> how they do it. For example: >> https://lkml.kernel.org/r/CANUX_P3F5YhbZX3WGU-j1AGpbXb_T9Bis2ErhvKkFMtDvzatVQ@xxxxxxxxxxxxxx > > After >> > enabling it on both ends ( despite the root port still claiming > it is not supported ) I still see ~121 watts according to the > Kill-A-Watt my system is plugged into. Oh well. ASPM only saves power when the PCIe link is idle. I'm not a video person, so I don't know how video usage translates into link usage, and I don't know how much power it saves. My guess is that the amount is fairly small and might not be measurable with a Kill-A-Watt. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
