On 01.05.2016 21:40, Daniel Kulesz wrote:
Hi again,
I did some more experiments with the vendor BIOS and made the following observations:
- disabling "cpu power management" makes the idle consumption raise to 12,8W
Is this 12.8W compared to 7.5W (i.e. with lowest backlight)?
- disabling "PCI Bus power management" and "PCI express power management" makes the idle consumption raise to 13,3W
- disabling the AMT firmware had no effect
- running the stress test still drains only 24,2W
- performance is the same as before
I still don't understand the whole performance issue. Therefore, I took another X200 with a P8600, CCFL screen and an older vendor BIOS and re-ran the benchmark there --- with almost identical results.
So in the end I'm just confused. This would mean that running Coreboot makes the X200 *much* faster at the expense of battery life, both in idle and under stress conditions.
Maybe Lenovo limited the processor clock on purpose to get a better battery life. Maybe it's just an unexpected side effect of running Linux (not Windows, what Lenovo tested against). Anyway, I wouldn't care about the power consumption under load, it might even result in a longer battery life: Being faster means shorter periods in higher performance states. The idle power consumption is what really matters.
Any ideas which could solve this mystery?
One more thing you can test, in case your Linux uses the intel_idle driver: There is a kernel parameter intel_idle.max_cstate, if you boot the vendor BIOS with defaults and Linux with intel_idle.max_cstate=2 it should use C1/C2 but not C3/C4 and thus behave more like coreboot.
Nico