[coreboot] KGPE-D16: More power drain experiments with coreboot vs. vendor bios

[Daniel Kulesz]

Hi all,

I did some more testing with the Opteron CPUs, and it seems there is some defect in coreboot as it does not report the state P5. I attached the output of "cpupower frequency-info" which I obtained on a 1x6220/64G configuration running coreboot and running the vendor bios.

I also did some wattage measures using a new Brennenstuhl PM 231 watt meter for my whole system. It seems like coreboot still has some flaw in this regards, as I was able to reproduce the high power drain in idle with the 6220 processor as well.

With the vendor bios:

2x6276, 128G => 90W idle, ~350W load
1x6276, 64G => 66W idle, 165W load
1x6220, 64G => 70W idle, 157W

With coreboot:

1x6220, 64G => 101W idle, 165W load

One thing I noticed is that when running coreboot the power state P5 seems absent, while it's present when running the vendor bios. Could this be the cause for the high power drain in idle? (even if I am not sure if the system enters these states at all). Please see the logs attached.

If you compare the config of 1x6276 vs. 2x6276 it seems like there is just a difference of 24W in idle and I am sure the memory also draws some power. Therefore, I wonder how big the improvement could be by replacing the 6200-series CPUs by one of the power-optimized "warsaw" modules (6338P or 6370P). I could not find any figures about idle power consumption with these CPUs so I welcome any reports from others. I don't really need all that CPU power but I would really like to use all of my 128G memory - which is why I am looking for the most power efficient CPU for the KGPE-D16.

Cheers, Daniel
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